Monday

January 16, 2017
Number of results: 4,565

**For Reiny**

If you could go back and check my reply to you. thanks

*September 5, 2012 by Vanilla Bear*

**trig-reply 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 ...

*January 3, 2011 by Carol*

**Reiny+Damon**

Can you reply to my last math+log post =) thanks. I'm going to be having alot of math questions today.

*February 23, 2009 by Chopsticks*

**Math w/reply**

Hey there, just need help with these two. I need someone to help explain them to me/break them down. 1. gr 1/100=_____mg Answer: 0.6 2. 0.3mg= gr_____ Answer: 1/200 3. gr iii /ss= ______mg Answer: 210 Thank you in advance! *** REPLY: I did not get these answers. These are the ...

*June 5, 2016 by Anonymous*

**Trig**

#1 (1/sinx)(sin^2x + cos^2x(sinx/cosx) )/(sinx + cosx) = (sinx + cosx)/(sinx+cosx) = 1 Reiny helped with this question but I don't how Reiny did it. Please explain

*February 21, 2012 by Anonymous*

**To Reiny**

Reiny could you please check my Calculus post below, it says Calculus--Reiny.

*October 4, 2011 by -Untamed-*

**trig**

Solve without using a calculator or tables cos(5pi/6 + pi/4) Thank you Reiny!:)

*May 1, 2008 by Priya*

**trig**

Solve the given triginometric equation analytically 7 sinx - 2 = 3(2 - sin x) If your are online, thank you my dear Reiny:) Priya

*May 1, 2008 by Priya*

**Math (Reiny??)**

Mrs. Reiny ... As in Harris County Mrs. Reiny?

*April 26, 2011 by sa*

**Reiny+ In need of help**

Hey Reiny, could you please take a look at my expo growth and decay post? Thanks alot.

*March 2, 2009 by Chopsticks*

**Reiny**

Reiny I think I have found out the rectangle problem. Could you check and see if Ive got it correct?

*January 19, 2011 by Sydney*

**math (final trig problem)**

Solve for x on the interval [0,π/2): cos^3(2x) + 3cos^2(2x) + 3cos(2x) = 4 I havent done trig for a while so what exactly does that mean in solving for x on that interval and how would i go about doing that? Where are you getting these tough trig questions?? how about ...

*April 30, 2007 by jacob*

**Reiny! Reiny! Reiny!**

1. Oanh walked from her home to the grocery store at 3 mi/h and jogged home at 6 mi/h. Her total round trip was 15 minutes (1/4h). How far from Oanh's home is the grocery store? (use an equation to solve this) Help, I am totally clueless on this.

*February 5, 2009 by Ellen*

**reply+chemistry please**

can someone reply to my last chem post

*February 4, 2009 by Chopsticks*

**reiny**

reiny why are you so smart thanks for aswering my question

*July 25, 2012 by amira*

**trig**

Solve the given triginometric equation analytically. Use values of x for 0 less than or equal to x less than 2pi P.S Thanks Reiny for your last post, if you are still online.

*May 1, 2008 by Priya*

**Chemistry+Reply**

Can someone reply to my previous post.

*January 15, 2009 by Chopsticks*

**drwls, or other tutors**

does my last postage seem correct for the answers that i got. The one that doesn't have a reply. See previous reply to your post.

*March 1, 2007 by jas20*

**Trig.......**

I need to prove that the following is true. Thanks (2tanx /1-tan^x)+(1/2cos^2x-1)= (cosx+sinx)/(cosx - sinx) and thanks ........... check your typing. I tried 30º, the two sides are not equal, they differ by 1 oh , thank you Mr Reiny I'll tell my teacher this Question is ...

*April 18, 2007 by abdo*

**reiny**

How do I find a variance for a set of numbers {1,16,8,17,12} I got that variance-34.2, but I'm unsure. Any help? Thanks. math - Reiny, Sunday, January 24, 2010 at 8:16pm look at his page. Reiny - April, Sunday, January 24, 2010 at 8:25pm I looked at that page and did my ...

*January 24, 2010 by April*

**TO REINY **

Hi reiny i just wanna say thank you for always answering my questions thanks for always helping me <3 thank you may god bless you

*December 5, 2013 by BARBIE LEE *

**reiny**

thanks reiny--but i'm in 6th gr and we r not studying powers..can you help me with a simpler answer without powers?

*November 12, 2009 by jane*

**Jiskha**

Jiskha homework help rocks. But I need someone to reply to my post: social studies!!!! -afton PLEASE REPLY!!!!!!!!!!! 10/9 - 9:21 pm

*October 9, 2006 by Anonymous*

**Calculus--Reiny**

Calculus - Reiny, Friday, December 23, 2011 at 6:59pm I read that as (4a^2-1)/(4a^2-16) * (2-a)/(2a-1) , my brackets are necessary = (2a+1)(2a-1)/( 4(a+2)(a-2) * (2-a)/(2a-1) the (2-a)/(a-2) are opposite, they will give you the -1 so.. = -(2a+1)/(4(a+2)) , again you have to ...

*December 25, 2011 by -Untamed-*

**chemistry+reply**

can someone reply to my previous chemistry thread please?

*January 21, 2009 by Chopsticks*

**Algebra-Reiny please explain this**

Hi Reiny, I posted this problem earlier and you responded but I don't get the reasoning- The problem was -2log8(x+1) = -8 you said multiply by -2 and then you put log8(x+1)=4(wasn't that dividing by -2) log8(x+1)^2 = 8 (how did you get to the power of 2 and =4 became =8 x+1 = ...

*December 13, 2010 by Anna*

**Urgent math question for Reiny**

Find the value of the expression below for r=4 and t=2.... t^3-r+20 divided by r 9*** 72 6 40 Ok, Reiny you said my answer9 was originally wrong, however when I looked at the work you did and you put in parenthesis()....my question is why, because the original expression didn'...

*September 4, 2013 by Gabby*

**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...

*February 23, 2009 by hayden*

**to reiny**

Reiny i got (x+5)(x-3) x=-5 or x=3

*December 28, 2008 by kiearra*

**Math thanks, Reiny**

Thanks Reiny!

*September 19, 2009 by Michael*

**English**

I am writing a letter, in the closing I wrote, If you reply by [a date].... or If you reply back by [a date].... Is the "back" necessary?

*June 24, 2008 by Bell*

**Pre-Calculus - Reiny**

Reiny you helped me with this logarithm yesterday: How did you write it out as log2 ( √A / B^3 ) Laws of logarithms combine, write as a single logarithm Need help on this question please, Im stuck, don't know where to go abouts from here: I did it on paint and uploaded ...

*October 17, 2012 by Shreya*

**URGENT~MATH For Steve or Reiny**

For questions 5-7, find the solution to the system of equations by using either graphing or substitution. 5)y=6-x and y=x-2 (1point) (2,4) (-4,2) (4,2) no solutions 6)y=2x-1 and y=x+3 (1point) (4,7) (7,4) (-7,-4) no solutions 7) y=4x and y+x=5 (1point) (-4,1) (1,4) (-3,2) (2,3...

*May 7, 2013 by Gabby*

**Maths - Reiny**

Show that the equation 3x^2 - x^3 + 3 = 0 can be rearranged to give: x = 3 + 3 ---- x^2 x^3 = Divide by ? = x = 3 + 3 ---- x^2 Using Xn+1 = 3 + 3 with x0 = 3.2 ---- x^2n find the values of x1 x2 and x3? What to the values of x1 x2 and x3 represent? The represent estimates of a...

*January 3, 2017 by Elle*

**TO REINY**

Thank you Reiny, Why I have to divide 632/1.05? I was dividing 632/0.05, I need to understand for future similar problems, I really appreciate your help, I finished school almost 30 years ago, I decided to go back to school an obtain a degree, I try my best but so many years ...

*January 25, 2015 by maribel*

**Calc I (@Reiny) **

y = x^3 - 8x^2 + 6x -2 has a slope of 6 at two points, what are the coordinates? I used Reiny's way to help solve this answer. Please check if I've done it correct: y'= 3x^2-16x+6 3x^2-16x+6=6 3x^2-16x=0 x(3x-16)=0 Solve for x's x=0 3x-16=0 ~> x=16/3 Plug x values to ...

*October 10, 2016 by Angie*

**Calc I (@Reiny) **

y = x^3 - 8x^2 + 6x -2 has a slope of 6 at two points, what are the coordinates? I used Reiny's way to help solve this answer. Please check if I've done it correct: y'= 3x^2-16x+6 3x^2-16x+6=6 3x^2-16x=0 x(3x-16)=0 Solve for x's x=0 3x-16=0 ~> x=16/3 Plug x values to ...

*October 10, 2016 by Angie*

**Math: Reiny **

I already posted this question, and Reiny had a question about the question. How many square units are in the region satisfying the inequalities y>=(x) and y<=-(x)+3? Express your answer as a decimal. * the () are absolute value signs. •Math - Reiny, Wednesday, ...

*December 3, 2014 by Jenny *

**trig**

e.g. tan 315 = -1, does that work in our equation ?? Yes, thank you again Reiny! My next question is to find sin theta and cos theta. cos 2theta = 1/3 and pi less than or equal to 2theta less than or equal to 2pi I hope Im not overburdening you with question:/

*May 1, 2008 by Priya*

**Thank you Jiskha and Reiny**

I just wanted to write a post to thank everyone who helps out. I haven't found people to be very grateful on this site so I thought i'd take a moment to tell you how awesome you guys are. Special thanks to Reiny for all the helpful math tips. You have helped me through a lot ...

*January 17, 2013 by Anonymous*

**Reiny or Damon or Bobpursley **

Express the series 11 + 18 + 27 +...+ 171 using sigma notation. Usually you would take 27-18 and that's the step between numbers, right? (I think its the k-value?) But 27-18=9 and 18-11=7. Are we stepping by k+2 here? Like k, k+2 k+4, k+6...? Please help me. I'm not confident ...

*April 27, 2012 by Tabby*

**Math( Attn: Reiny)**

1. A rental business charges $12 per canoe and averages 36 rentals a day. For every 50-cent increase in rental price, it will lose two rentals a day. What price would yield the maximun revenue? I was told the answer by Reiny, but I couldn't get the right answer. I found the ...

*January 25, 2015 by Wendy*

**trigonometry**

---I asked this question Solve the following right triangles: a. a=117 ft, b=16.35 ft b. B=8 degrees 29',and a=32.8 ft Reiny was kind enough to post this reply. "solving" a triangle involves finding all missing sides and angles, so in a) you found the sides, but still no angle...

*January 16, 2011 by Jad*

**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 ...

*February 13, 2016 by sim*

**Thank you (bobpursley)! (no reply needed)**

No reply needed.

*January 13, 2007 by EinstNewtLieb*

**Algebra **

I already posted this question and Reiny answered it, I just wanted to clarify my answer Problem: If f(x) is a polynomial of degree 4, and g(x) is a polynomial of degree 2, then what is the degree of polynomial f(x)-g(x)? Reiny: so f(x) has to contain an x^4 term and g(x) does...

*November 12, 2014 by Trish Goal*

**Throughout your life,who has impacted your life?**

Opinions are ok but anything with identifying information will be removed. In fact, why don't you retype your question and omit the part about including name, address, et al. and we can get someone to remove your original post. ok.thanks,do you think you can reply also.?I'd ...

*February 9, 2007 by DrBob222*

**Reiny! Reiny! Reiny! Answer Check and HW Help!**

Translate to a system of equations and solve: 1) The sum of two numbers is 36. One number is 2 more than the other. Find the numbers. Answer: (17,19) 2) Find two numbers whose sum is 66 and whose difference is 18. Answer: (37,29) These ones I am not sure of: 3) The difference ...

*February 12, 2009 by Britney*

**precalc**

Suppose that z1=6-8i. Find: A. The Trig Form of the complex number z1, where your theta is in degrees. B. The Trig form of z1*z2, where z2=5[cos(60degrees)+isin(60degrees)] C. The Trig Form of (z1)^4

*December 5, 2011 by Joshua*

**calculus**

1. what trig function has an amplitue of 1 and negative values for angles between π/2 and π? 2. what trig function never crosses the x-axis and has a value of 2 at π/6? are these correct? 3. what trig function has a period of π and is undefined for -π/...

*September 28, 2015 by anon*

**math**

Posted by connie on Monday, July 20, 2009 at 11:56pm. Find the indicated outputs for f(x) = 2x²-4x f(0)= ____? f(-1) =____? f(2) =____? Responses math - Reiny, Tuesday, July 21, 2009 at 8:00am f(0) = 2(0)^2 - 4(0) = 0*0 = 0 f(-1) = 2(-1)^2 - 4(-1) = 2(1) + 4 = 2 + 4 = 6 now ...

*July 21, 2009 by connie*

**english**

help me to reply this letter from a friend in Britain,this letter is in my english book is not real but i have to write a reply. I'd love to come and stay with you.It will have to be in August because ,as you know, our summer holiday are not as long as yours. Tell me when the...

*September 28, 2010 by Anonymous*

**math**

could someone please refresh my memory of the basic trig functions? ex) cos^2 + sin^2 = 1? That is a trig identity. http://www.sosmath.com/trig/Trig5/trig5/trig5.html

*April 12, 2007 by raychael*

**Math**

To Reiny: Hi, thank you for your time Reiny and your info. I am so sorry but on the first one I accidentally put 0 where I should have put =9. In other words, the first equation should have said (9n+1)squared =9. Really sorry to have taken up your time with the wrong equation...

*November 3, 2013 by Brandi*

**Math**

Mrs. Hart, at age 65, can expect to live for 25 years. If she can invest at 5% per annum compounded monthly, how much does she need now to guarantee herself $900 every month for the next 25 years? math - Reiny, Friday, April 3, 2015 at 3:05pm Present Value = 900(1 - 1.0041666...

*April 3, 2015 by Judy*

**trig**

What kind of reflections are the following trig functions? y = 3cos(x-1) y = sin(-3x+3) y = -2sin(x)-4

*April 21, 2008 by Joshua*

**trig**

What is the shift along x of the following trig functions? y = (3sinx/2) + 4 y = -2sin(x)-4 y = sin(-3x + 3)

*April 21, 2008 by Amandeep*

**trig**

express the trig. ratios sinA,secA n tanA in terms of cotA.

*May 7, 2011 by Anonymous*

**trig**

How do you solve cos(2arcsin 1/4) using inverse trig. functions??!! PLEASE HELP ME!

*May 9, 2011 by Tor*

**Trig**

Find (if possible) the trig function of the quadrant angle. sec 3pi/2

*June 6, 2011 by Master chief*

**trig**

What kind of reflection does the trig function y = cos(4x/3 minus 1) have?

*April 21, 2008 by Priya*

**trig**

What kind of reflection does the trig function y = cos(4x/3 minus 1) have?

*April 22, 2008 by Chaitanya*

**trig**

how do i do this? give the signs of the six trig functions for each angle: 74 degrees?

*December 3, 2008 by Tay*

**trig**

simplify to a constant or basic trig function.. 1+tan(x)/1+cot(x)

*March 14, 2010 by hilde*

**trig**

find the 5 trig ratios when sin theta = -5/13 and lies in quadrant 3

*September 14, 2011 by karen*

**Trig**

Does anybody know a good website that will help me with finding the six trig functions of a point NOT on the unit cricle?

*September 16, 2009 by Anonymous*

**trig**

use the unit circle to find the exact value for all the trig functions of è=2ð/3.

*February 1, 2010 by Anonymous*

**Precalculus**

How would you solve this trig function: cos2x=sin^2-2 how do you know what trig identities to use?

*August 6, 2011 by Jess*

**Trig**

find the exact values of the six trig functions of angle... sin(-315degrees) how do i do this?

*September 1, 2011 by ALISON*

**trig**

I don't know to find the derivative of the following trig functions. Please help. f(x)= cotx h(x0= secx i(x)= cscx

*January 19, 2012 by Claire*

**trig**

I don't know to find the derivative of the following trig functions. Please help. f(x)= cotx h(x)= secx i(x)= cscx

*January 19, 2012 by Claire*

**trig**

find the 5 other trig functions if cos(theta) = square root of 2/2 and cotangent is less than 0

*June 9, 2010 by kelly*

**trig**

if (-12,5) is a pointon the terminal side of an angel 0 find the exact value of six trig funcation of 0

*June 19, 2014 by sal*

**trig**

what is the exact value of 7pi for all trig func.?

*February 1, 2010 by claire*

**Trig**

Find (if possible) the trig function of the quadrant angle.

*June 6, 2011 by Master chief*

**trig**

write a product of two trig functions that equals 1.

*November 6, 2011 by Dani*

**Trig**

Solve the following trig equation 2cos(x-π/6)=1

*January 31, 2012 by Matt*

**Trig **

csc thea= -2, quadrant 4. what are the six trig functions?

*May 6, 2013 by Shay*

**trig**

TRIG Identities, Gr. 12: Prove: cot4x=1-tan^2x/2tan2x

*May 23, 2013 by Josh*

**probability**

Reiny, thanks!

*September 24, 2011 by dee*

**ThankYou Reiny!!!**

Thank you!

*January 29, 2012 by Betty*

**Maths**

Thanks Mr Reiny

*May 12, 2013 by Gibbs*

**Algebra 1 (Reiny)**

1. t^-6 for t = 2 A: 1/64?

*January 31, 2014 by Anonymous*

**Algebra 1 (Reiny)**

1. ((d + 2)/(d + 8)) = ((-6)/(d + 8)) A: ? 2. 4/n^2 = 7/n + 2 A: n = -4 or n = 1/2? 3. 2/t + 4/3t = 4/t + 2 A: t = 10? 4. ((x -6)/(x^2-6)) = ((-4)/(x-4)) A: ?

*June 3, 2014 by Victoria*

**trig**

What is the shift along x of the trig function y = cos(4x/3 minus 1)? Any link of proof would be appreciated if you have one Thank you

*April 21, 2008 by Priya*

**trig**

What is the shift along y of the trig function y = cos(4x/3 minus 1)? Any link of proof would be appreciated if you have one Thank you

*April 21, 2008 by Priya*

**trig**

Let Q be an acute angle such that sinQ=.6. Find the values of the following using Trig Identities: cosQ and tanQ

*July 27, 2010 by student*

**Trig**

Use Trig identities to verify that sec^4(x)-tan^4(x)=1+2tan^2(x), Only work with one side of the equation

*March 1, 2011 by Anonymus*

**Please help me with trig.**

One more problem.. Given sin t= 3/11 and cos t<0, find the values of the remaining 6 trig functions.

*January 27, 2016 by Jane*

**trig**

how to i find the six trig values for (7pi/3)

*January 12, 2010 by Rak*

**trig**

what's the single trig. function of cos6xcosx-sin6xsinx

*May 17, 2012 by MIK*

**Science**

Lack of oxygen in a pond may be a limiting factor. True or False? Please reply ASAP, thanks Lack of oxygen in a pond may be a limiting factor. True or False? Please reply ASAP, thanks Please only post your questions once. Repeating posts will not get a quicker response. In ...

*May 18, 2007 by Marry*

**trig**

Suppose that q is in standard position and the given point is on the terminal side of q. Give the exact value of the indicated trig function for q.

*February 21, 2011 by Anonymous*

**THANKS FOR YOUR HELP DAMON AND REINY!! :)**

thanks alot!

*May 8, 2008 by Miley*

**algebra**

Thank you Poppy and Reiny!!!!!!!!!!!! :)

*May 5, 2010 by paul*

**Algebra 1 (Reiny)**

12a - 11 = 9a - 1?

*October 7, 2013 by Anonymous*

**Algebra 1 (Reiny)**

Is -1/64 the answer to 2x^0y^-3?

*January 18, 2014 by Anonymous*

**Math @Reiny**

Did I do #2 right? 2.) (1-2i)/2i (1-2i)/2i = (1-2)/i x i/i = (1i-2i)/i^2 = (1i+2) =2+1i

*October 8, 2014 by Ben*

**math**

A lady buys goods worth Rs.200 from a shop. (shopkeeper selling the goods with zero profit) .. The lady gives him 1000 rs note. The shopkeeper gets the change from the next shop and keeps 200 for himself and returns Rs.800 to the lady. .. Later the shopkeeper of the next shop ...

*March 10, 2014 by faizanurrahman*

**trig 26**

simplify to a constant or trig func. 1. sec ²u-tan ²u/cos ²v+sin ²v change expression to only sines and cosines. then to a basic trig function. 2. sin(theta) - tan(theta)*cos(theta)+ cos(pi/2 - theta) 3. (sec y - tan y)(sec y + tan y)/ sec y combine fractions and simplify ...

*March 14, 2010 by hilde*