Hi i posted this before but I wanted to ask Bobpursley a few questions on his reply 1)For the first function you used cosine when they ask for sin, why is that?
89,047 results

Precalc(attn Bobpursley)
Hi i posted this before but I wanted to ask Bobpursley a few questions on his reply 1)For the first function you used cosine when they ask for sin, why is that? Also why did you put .5 in the beginning and end of the function? 2)For the second question why did you put 10 in ... 
Jiskha
I typed several questions and answers regarding the subject of Geography, and suddenly, as I was waiting for a reply from Ms. Sue, it seemed as though my questions were deleted from the webpage where all of the other questions are posted. I do not know where I may be able to ... 
PreCalc
I am really struggling with how to do these problems, I posted them a few minutes ago but the answers/work shown was incorrect. 1) a) Use an Addition or Subtraction Formula to write the expression as a trigonometric function of one number. cos 12° cos 18° − sin 12° ... 
inverse
If f(x)=cosx + 3 how do I find f inverse(1)? Thanks y = cos(x) + 3 the inverse of this is x = cos(y) + 3 solve for y and you have your inverse The cos function only has a range of [1,1], so the range of f(x) is [2,4]. this means f inverse of 1 doesn't exist. I didn't ... 
Math HELP!
I posted a few questions and then went back and posted how I thought they were supposed to be answered. Could someone please locate my earlier questions and tell me if I am on the right track? 
Math  derivative of sinusoidal (check)
a) Find a function y=f(x) that satisfies the differential equation dy/dx = fifth derivative. This is one of the questions in my practice test, I tried the basic equation of the trig function such as f(x)= sin(x) or f(x)=sin(x) however in the fourth derivative they reach the ... 
PreCal: Word Problem
I'm having a lot of trouble on this word problem. Can someone help me plz? To define the inverse sine function, we restrict the domain of sine to the interval ______. On this interval the sine function is onetoone, and its inverse function sin^−1 is defined by sin^&#... 
trigreply to Reiny
RE: ( sin (x/2) /( 2 sin (x/2) + cos (x/2)) is an alternate representation for, 1 / ( 4 tan (x/2) + 2 ) Thanks for your help, sorry I posted 3 times, I thought you didn't understand what I needed. I really do appreciate your time spent. just for your FYI, if you are ... 
Math CONTINUATION OF QUESTION FROM bobpursley
Thank you for answering the question before bobpursley, I understand how you did the deriv of inside, outside, but how do I now do the second derivative since you have the extra 18x^2 in the numerator?? Thank you very much! (I suppose I have to brush up on my derivatives) ... 
another precal
i have two questions for you to check please! 6cos^2x+5cosx4=0 where 0degrees < or equal to 0 which is < or equal to 360. I got that this factors to (3x+4)(2x1) so the answer is x= 4/3 and x= 1/2 ?? right? and the second question: determine sin2theta, cos2theta, and ... 
ATTN bobpursley
On Thursday October the Second, you gave a reply to "martha" regarding the movie chariots of fire. I have posted a response there of my own because I feel that your feedback was misguided. Could you please read my message and then get back to me? 
Physics recheck
Let f be the frequency, v wav the speed, and T the period of a sinusoidal traveling wave. The correct relationship is: a)f=1/T b)f=vwav + T c)f=vwavT d)f=vwav/T e)f=T/vwav My thoughts: Since frequency is equal to T=1/f so f=1/T. Vwav is connected to f by the equation v=lambda... 
Trig
Given: cos u = 3/5; 0 < u < pi/2 cos v = 5/13; 3pi/2 < v < 2pi Find: sin (v + u) cos (v  u) tan (v + u) First compute or list the cosine and sine of both u and v. Then use the combination rules sin (v + u) = sin u cos v + cos v sin u. cos (v  u) = cos u cos v + ... 
math
Eliminate the parameter (What does that mean?) and write a rectangular equation for (could it be [t^2 + 3][2t]?) x= t^2 + 3 y = 2t Without a calculator (how can I do that?), determine the exact value of each expression. cos(Sin^1 1/2) Sin^1 (sin 7pi/6) x= t^2 + 3 y = 2t ... 
Trig
In ABC, vertex C is a right angle. Which trigonometric ratio has the same trigonometric value as Sin A? A Sin B B Cosine A C Cosine B D Tan A 
DEAR REINY
dear reiny i am sim who posted 4 questions this morning i am in dubai and my final examinations are after 13 days and by the way those questions were not my homework or assignment those were some sums which we get on our school website and i had a doubt in those questions but ... 
the novel "Ordinary People" by Judith Guest
Has anybody read this book? I have a few questions to ask, I've read the book but forgotten a few things reply ASAP! 
Calculus
How do I graph sin and cosin example: graph y=4sin(x + 3.14) Your function is the sin function shifted by pi units to the left. You need to study the sin function and know how to graph it. There should be a picture of it in your text, it's a very commonly used funtion that ... 
English (parts of speech)
1)Few comic strip are really comical 2)Few attended the meeting (Few is: adjective, verb ,adverb, preposition) (the first and the second are different 3)Before the telecast, we were all nervous 4)Before you leave, let me have your address Before is in the two sentences:Noun,... 
english
For questions 1315, select the answer that correctly identifies the part of speech of the all caps word. 1. Katrina wanted to vist her grandmother AND grandfather over the weekend. a. conjuntion b. noun 2. "OH" her mother said, "why don't we go Saturday. a. noun b. ... 
trig
Reduce the following to the sine or cosine of one angle: (i) sin145*cos75  cos145*sin75 (ii) cos35*cos15  sin35*sin15 Use the formulae: sin(a+b)= sin(a) cos(b) + cos(a)sin(b) and cos(a+b)= cos(a)cos(b)  sin(a)sin)(b) (1)The quantity = sin(14575) = sin 70 = cos 20 note that... 
Computer Questions
I posted some computer questions and my answers on Saturday. They should be on somewhere between pages 2 through 10. would you please check my answers for me? There are about 16 questions and answers. Thank you!! It will say "computer questions" Thank you. Yup. I got it :) But... 
Cosine Math Question
Graph a cosine function whose amplitude is 4, period is π , midline is y=−3 , and yintercept is (0, 1) . The first point must be on the midline and the second point must be a maximum or minimum value on the graph closest to the first point. I appreciate the help thanks 
Calculus
The motion of a spring that is subject to dampening (such as a car's shock absorber)is often modeled by the product of an exponential function and a sine or cosine function. Suppose the equation of motion for a point on such a spring is s(t)=3∗e^(−2t)sin(3ðt) ... 
Calculus
1) The period of a trig. function y=sin kx is 2pi/k. Then period of y=sin^2(pi.x/a) should be 2pi/(pi/a)=2a, but somewhere it is given as a. Which is correct? 2) The period of r=sin^3(theta/3) is given as 3pi. How is it worked out? Is it because after theta=0, the function ... 
TRIG!
Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6 x=1  (3/4)sin^2 2x work on one side only! Responses Trig please help!  Reiny, Monday, February 23, 2009 at 4:27pm LS looks like the sum of cubes sin^6 x + cos^6 x = (sin^2x)^3 + (cos^2x)^3 = (sin^2x+cos... 
Trigonometry
IM STUCK ON THESE :( 1. What is the equation for shifting the standard sine curve +2 units horizontally? A. y = sin (x + 2) B. y = sin x + 2 C. y = sin x − 2 D. y = sin (x − 2) 3. What is tan¹ √3/3 ? A. π/4 B. π/3 C. π/6 D. π/4 4. cot... 
Trigonometry
IM STUCK ON THESE :( 1. What is the equation for shifting the standard sine curve +2 units horizontally? A. y = sin (x + 2) B. y = sin x + 2 C. y = sin x − 2 D. y = sin (x − 2) 3. What is tan¹ √3/3 ? A. π/4 B. π/3 C. π/6 D. π/4 4. cot... 
Math
Rewrite the expression in terms of the first power of cosine sin^4(x) 
calculus
rewrite the expression in terms of the first power of the cosine. sin^8x 
Spherical Trigonometery
I am trying to apply the formula cos c = cos a x cos b + sin a x sin b x cos C to find the length of c in my spherical triangle. I am working with 2 examples in a book in which the answers are given. In the first example all the sines & cosines calculated are positive and I ... 
Trigonometry
Use the powerreducing formulas to rewrite the expression in terms of the first power of the cosine. [#1.] (sin^4x)(cos^4x) [#2.] (sin^4x)(cos^2x) 
Calculus
After t hours of an 8hour trip the distance a car travels is modeled by: D(t)= 10t + (5)/(1+t)  5 where D(t) is measured in meters. a) derive a formula for the velocity of the car. b) how fast is the car moving at 6 hours? c) derive a formula for the car's acceleration. I'm ... 
Math
rewrite the expression in terms of the first power of cosine. cos^3(x)sin^4(x) 
Trigonometry
rewrite the expression in terms of the first power of cosine. cos^3(x)sin^4(x) 
Math
Rewrite the expression in terms of the first power of the cosine sin^8(x) how do i do this plz help !! 
Calculus
Consider the function f(x)=sin(1/x) Find a sequence of xvalues that approach 0 such that sin (1/x)=0 sin (1/x)=1 sin (1/x)=1 Is sin sin (1/x)=0 and sin (1/x)=1 does not exist. What is sin (1/x)=1 then. 
Physics  Frequency
This is in reply to a previous post, I'm not really sure whether replies to posts that are several days old are viewed by anyone, so I'm reposting just in case. In reply to bobpursley's post, I just want to ask, how would you know how long it takes for the sound to reach you? ... 
To: Bobpursley
Thanks for your reply! I have some questions about my AMERICA ONLINE service that's why I asked "How can I email to America Online? Is there any website where I can write my comments or questions to America Online? (Like Feedback) I found a website on GOOGLE but there was a ... 
Graphing trigonometric function
sine and cosine have a period 2pi tangent and cotangent have period pi Can someone explain why? thanks a lot. well tangent is sine/cosine and there a place where the tangent function is undefined and that is where the asymptotes occur. the same is true with the cotangent since... 
sine and cosine
Simplify and write the trigonometric expression in terms of sine and cosine: sin x + (cot x)(cos x) = (1/f(x)) f(x)= ? 
Math 2nd question
Express as a single sine or cosine function (note: this is using double angle formulas) g) 8sin^2x4 I just don't get this one. I know it's got something to do with the 12sin^2x double angle formula. It's the opposite though? :S h) 12sin^2 (π/4x/2) = 1sin^2(π/4x... 
@Kemon
I deleted your 19 questions because you showed none of your work and posted no answers. If you'd like us to check a few of your answers, please repost no more than five questions along with your answers. 
Reply to grant about a regression problem
This is a reply to the question posted here http://www.jiskha.com/display.cgi?id=1178989522 As I explained there, you can find the parameters by defining: x1 = Sin(0.49 t) x2 = Cos(0.49 t) and treat this as an ordinary linear regression problem. If we denote the height by Y, ... 
Algebra
89. Solve for x in the equation: 6/7x  6 = 2 I posted this before, and this is the reply I got from someone: multiply both sides by 7 6x42=14 add 42 to each side 6x=28 x=14/3 But I don't get how this is done because to eliminate 6/7 shouldn't I multiply by 7/6, and not ... 
Algebra II
Part 1: Using complete sentences, compare the key features and graphs of sine and cosine. What are their similarities and differences? Answer: The sine graph will always pass through (0, 0), While the cosine graph wouldn't. If the graph is 2cosx, it will pass through (0, 2). ... 
Math PLEASE HELP
No one was answering my questions for the first question I posted so I posted it again. answers for 12345: 1. 9 3/5 2. 4 1/2 3. 4 3/4 4. still 7 6/9 5. still 10 16/18 
Math (trigonometric identities)
I was given 21 questions for homework and I can't get the last few no matter how hard and how many times I try. 17. Sinx1/sinx+1 = cos^2x/(sinx+1)^2 18. Sin^4x + 2sin^2xcos^2x + cos^4x = 1 19. 4/cos^2x  5 = 4tan^2x  1 20. Cosx  sinx  cos^3x/Cosx = sin^2  tanx 21. Sin^2x... 
Calculus
Consider the function f(x)=sin(1/x) Find a sequence of xvalues that approach 0 such that (1) sin (1/x)=0 {Hint: Use the fact that sin(pi) = sin(2pi)=sin(3pi)=...=sin(npi)=0} (2) sin (1/x)=1 {Hint: Use the fact that sin(npi)/2)=1 if n= 1,5,9...} (3) sin (1/x)=1 (4) Explain ... 
Calculus
Consider the function f(x)=sin(1/x) Find a sequence of xvalues that approach 0 such that (1) sin (1/x)=0 {Hint: Use the fact that sin(pi) = sin(2pi)=sin(3pi)=...=sin(npi)=0} (2) sin (1/x)=1 {Hint: Use the fact that sin(npi)/2)=1 if n= 1,5,9...} (3) sin (1/x)=1 (4) Explain ... 
Trig
Solve in terms of sine and cosine: sec(x) csc(x) sec(x) sin(x) so far I have: 1/cos(x) 1/sin(x)  1/cos(x) sin(x) I am not sure where to go to from there. The book says the answer is cot(x) or cos(x)/sin(x) Thank you in advance. 
CALC
Let f(x) be the function e^sin(x/10). If you wanted to estimate the area under the curve for this function from 3 to 5, how many intervals would you need to use to be sure that your upper and lower bounds differered by no more than .01? 
math
Use the formulas for lowering powers to rewrite the expression in terms of the first power of cosine. sin^6(x) Answer=__________ ~Thank you. 
drwl / bobpursley please check
I had posted three questions at 1:48pm, 2:40pm and 2:41pm and I am having problems with them. Can you please check them for me. Thanks! Repost if you are not satisified with the responses. 
Math repost
I posted this question before at 7:14 I think the answer to it is 0. cot(40)  ((sin(50))/(sin(40)) = ? these are also degrees steps too please. I thought since 50+40= 90 then that part would be 1, but then how would cot 40 turn out to be 1 
gnozahs
I removed about ten questions you posted this morning. There was no indication of what you had done, what your thinking was, or what you wanted from us. We are not going to do homework for you. If you want hints on these calculus questions, say so, or ask what you want. Just ... 
pre calc
The Identity Function The Squaring Function The Cubing Function The Reciprocal Function The Square Root Function The Exponential Functional Lo The Natural Logarithum Function The Sine Function The Cosine Function The Absolute Value Function The Greatest Integer Function The ... 
math
actually, in a addition to the question i posted a few minutes ago, can someone please help me with a few actual specific questions? thanks so much i'm very confused and i've been working on these all day. *Literal Equations* ~solve for x ax + bx = 8ab ~solve for y my  ny = m... 
Calculus  Second Order Differential Equations
Posted by COFFEE on Monday, July 9, 2007 at 9:10pm. download mp3 free instrumental remix Solve the initialvalue problem. y'' + 4y' + 6y = 0 , y(0) = 2 , y'(0) = 4 r^2+4r+6=0, r=(16 +/ Sqrt(4^24(1)(6)))/2(1) r=(16 +/ Sqrt(8)) r=8 +/ Sqrt(2)*i, alpha=8, Beta=Sqrt(2) y(0)=2... 
Physics (CHECK)
One student is pushing on a chair with a force of 260.6 N directed at an angle of 30 degrees above horizontal while a second student pushes on the same side of the chair with a force of 21.0 N at an angle of 15 degrees below horizontal. What is the magnitude, in N, of the sum ... 
@Incognito
I'm putting you in timeout for a few days so you can think about a few things. 1. Do not post in allcaps. It's considered shouting (and rude) online. 2. If you don't like how this website is run, go find another. 3. If you have homework questions, then ask them and have ... 
To Fay1985  math
Your post was removed. Please tell us your thinking on the 25 questions you posted. Attempt some answers, and we'll be glad to help you. Also  I don't believe that you posted complete information for many of the questions. 
English
Which sentence is correct: I wanted to tell you something before I head to town. or I wanted to tell you something before I headed to town. I think it is the first one, but I'm not sure. 
french  final draft
Well.. i posted this before and I reedited a few things. I need suggestions and editing please :) 
Quantum mechanics, eigenfunctions!
Determine if the function sin(x)*e^(ax) where a=constant is an eigenfunction of the operators d/dx and d^2/(dx)^2 Okay. My understanding is that you use the operator and perform its "thing" on the function. In this case, you will have to find the 1st derivative of sin(x)*e^(ax... 
Thank you (bobpursley)! (no reply needed)
No reply needed. 
math;)
Show that sin(x+pi)=sinx. So far, I used the sum formula for sin which is sin(a+b)=sin a cos b+cos a sin b. sin(x+pi)=sin x cos pi+cos x sin pi I think I am supposed to do this next, but I am not sure. sin(x+pi)=sin x cos x+sin pi cos pi If that is right then I am not sure ... 
Calculus
Hello. I have a few questions from my study guide, that I need to know to study for my test. 1) x^(2/3)*((5/2)(x) a) determine the ordered pairs of the local extrema of the function. Use the second derivative test. B) determine the ordered pairs of all inflection points of ... 
Business Communications
Write a business letter to the company or organization that's offering something you want and ask four questions that are important to you. Be sure to include enough background information, so the reader can answer your questions satisfactorily. Hollywood Vacation Giveaway 123... 
Calculus
Hello, I just wanted to verify if my work was good. Calculate the following integral by parts: ∫ upper limit is 1/5 and lower limit is 1/10. of 10sin^1 (5x)dx so first I named the variables: u = 10 sin^1 (5x) du = 50 / sqr(125x^2) dv = dx v = x so we get: = 10 sin^1... 
ok (my posts mysteriously vanishes...)
I posted a reply thanking both bobpursley and dr.bob (mild criticism)... I don't see the post. What happened? Was it removed? I saw your post thanking Bob Pursley and me. Many thanks for the thanks. All of us like to think that we lend a helping hand. Both individually and as ... 
Math Algebra
hi guys need help with a few questions. 1. Which equation represents the axis of symmetry of the function y = 2x^2+4x6? A. y= 1 B. x= 1 C. x=3 D x= 3 2. & 3. What are the coordinates of the vertex of the graph of the function  2. y = x^2+6x11 A. (3,2) B. (3,16) C. (3,... 
physics Again
bobpursley can you please check my reply to your post about my question? I am not sure if I did my equation correctly. Thanks 
precalculus
Rewrite the following expression as an algebraic function of x sin(arccos(x/2)) I know sine is y, which is opposite over hypotenuse. I also know that arccos is the inverse of cosine. I'm confused on what the question is asking and what to do with the x. Please help! Thanks 
algebra 2
Posted by hellogoodbie on Saturday, January 16, 2010 at 3:24pm. Posted by hellogoodbie on Saturday, January 16, 2010 at 2:59pm. How is this problem done? IF f(x)=2x^28x3 FIND f(2) algebra 2  bobpursley, Saturday, January 16, 2010 at 1:42pm Put in for x the value 2, and ... 
calculus
Could someone check my reasoning? thanx Find the derivative of the function. sin(sin[sinx]) I need to use the chain rule to solve. So I take the derivative sin(sin[sinx) first. Then multiply that by the inside which is the derivative of sin[sinx]. And multiply that by ... 
Math
The graph of a trigonometric function oscillates between y=1 and y=7. It reaches its maximum at x= pi and its minimum at x=3pi. which of the following could be the equation of the function? A) f(x)=4 cos x/23 B) f(x)=4 sin x/23 C) f(x)=4 sin 2x3 D) f(x)=8 sin x/23 
Calculus
Hello, Could somebody kindly check my answer for the following question? Find the derivative of the following function: h(x)=3e^(sin(x+2)) h'(x)=3'(e^(sin(x+2))+3(e^(sin(x+2))' h'(x)=0(e^(sin(x+2))+3(e^(sin(x+2))(cos(1)) h'(x)=3cos1(e^(sin(x+2)) I would greatly appreciate your... 
MATH
1.)Find the exact solution algebriacally, if possible: (PLEASE SHOW ALL STEPS) sin 2x  sin x = 0 2.) GIVEN: sin u = 3/5, 0 < u < ï/2 Find the exact values of: sin 2u, cos 2u and tan 2u using the doubleangle formulas. 3.)Use the halfangle formulas to determine the ... 
Math
1) Prove that for every x>=0 and 0<a<1 x^aax<=1a 2)prove that for 0<=x<=1: x^m*(1x)^n<= (m^m*n^n)/((m+n)^(m+n)) can someone please guide/help me in about how to solve and or approch these questions? (I know I have already posted it before but i think it... 
math
i have a few questions cosx + cosx =2secx   1+sinx 1sinx cos(xB)cos(xB) = 2sinxsinB csc2x= 1 secx cscx  2 cotx= cos5x+cos3x  sin 5xsin 3x 
physics
anyone who knows the answer to this question please show your work. drwls i know i posted this queestion before but you didn't reply to my comment. Your friend has climbed a tree to a height of 6.00 m. You throw a ball vertically up to her and it is traveling at 5.00 m/s when ... 
Sciencebobpursley
Thanks for helping me with al those parts bobpursley. If you have time, can you also check my questions please. Thank you very, very much in return. My post is on the second page. 
math 140
I have two questions posted that has not been answered please help. The questions were posted on March 18 please help. 
AED
I know I posted this but AI wanted to pose what i have so far and need more info. I have this so far: The handson learning in a science classroom when few resources are provided by the school can be the discovery bottles that the teacher can make, sensory table and you can do... 
Trig
Simplify sin x cos^2xsinx Here's my book's explanation which I don't totally follow sin x cos^2xsinx=sinx(cos^2x1) =sinx(1cos^2x) =sinx(sin^2x) (Where does sine come from and what happend to cosine?) =sin^3x 
Calculus
Consider the function f(x)=sin(1/x) Find a sequence of xvalues that approach 0 such that sin (1/x)=0 sin (1/x)=1 sin (1/x)=1 Is sin sin (1/x)=0 and sin (1/x)=1 does not exist. What is sin (1/x)=1 then. How would I show the sequence of values, any help would be greatly ... 
Physics
A vertical spring with a spring constant of 450 N/m is mounted on the floor. From directly above the spring, which is unstrained, a 0.30 kg block is dropped from rest. It collides with and sticks to the spring, which is compressed by 3.0 cm in bringing the block to a momentary... 
Calc
Find the exact total of the areas bounded by the following functions: f(x) = sinx g(x) = cosx x = 0 x = 2pi I set my calculator to graph on the xaxis as a 2pi scale. The two functions appear to cross three times between x = 0 and 2pi. (including 2pi) Now, from top to bottom, ... 
Math
Hi, this is a question I posted a couple of days ago and answers below.I am still really confused and unfortunately can't copy a picture into this. I thought it would be yx but have no idea how to calculate that, but as the pistons move in towards each other, wouldn't the ... 
Physics
Why is sin theta used in the torque formula while the work formula uses cosine theta? 
question+ stuck
how is the graph of f(x)= x^24x be used to obatin the graph of y=g(x)? I am stuck and unsure how to get out of this one so can you please help? thanks! You must define g(x). Is g(x) the inverse function of f(x)? well the function f(x)= x^24x has two zeros x= o and x4 Yes. ... 
Health
Hi again..sorry I havn't been asking questions these days as my sister (y912f) is always on :P I wanted to know whether it is better to brush your teeth after eating or before. Because mostly everyone does it before but I don't see the point when they're going to get dirty ... 
maths
Choose the two options which are true for all values of x 1) cos (x) = cos ( x – pie/2) 2) sin (x + pie/2) = cos (x – pie/2) 3) cos (x) = sin (x – pie/2) 4) sin (x) = sin (x + 4pie) 5) sin (x) = cos (x – pie/2) 6) sin^2 (x) + cos^2 (x) = pie would it be 1 and 3 ?? I ... 
Math (Trig)
sorry, another I can't figure out Show that (1cot^2x)/(tan^2x1)=cot^2x I started by factoring both as difference of squares. Would I be better served by writing in terms of sine and cosine? Such as: [1(cos^2x/sin^2x)]/[(sin^2x/cos^2x)1]=(cos^2x/sin^2x) 
Ms. Sue
Posted by Anonymous on Monday, February 17, 2014 at 9:02pm. Ms. Sue you banned me for giving answers to none existent questions, here only 2 questions were asked, quite a few people gave 3 answers. Why was I banned for this if other people do it. 
MATH
The graph of a trigonometric function oscillates between y=1 and y=7. It reaches its maximum at x= pi and its minimum at x=3pi. which of the following could be the equation of the function? A) f(x)=4 cos x/23 B) f(x)=4 sin x/23 C) f(x)=4 sin 2x3 D) f(x)=8 sin x/23 I think... 
MATH
The graph of a trigonometric function oscillates between y=1 and y=7. It reaches its maximum at x= pi and its minimum at x=3pi. which of the following could be the equation of the function? A) f(x)=4 cos x/23 B) f(x)=4 sin x/23 C) f(x)=4 sin 2x3 D) f(x)=8 sin x/23 I think... 
Pre Cal
how would i find the degrees of cos x= 3/2 if (0 <or= theta < 360)? i've tried putting it in my calculator with cosine^1 but im just getting err:domain. Please help! The cosine function only goes from 1 to +1. There is no solution to cos x = 3/2. thank you! 
Trigonometry
Can you show steps on deriving the identity from the sum and difference formulas for cosine: sin a sin b = (1 / 2)[cos(a – b) – cos(a + b)]