MATH
posted by MAKITA .
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 exact values of sine, cosine, and tangent of the angle: 15° .
4.) Use the sumtoproduct formulas to find the exact value of the expression:
sin 195°+ sin 105°
5.) Verify the identity algebraically:
(cos 4x  cos 2x)/2 sin 3x = sin x
THANKS IN ADVANCE!

MATH 
MAKITA
CORRECTION FOR NUMBER 2! THE PI SYMBOL DIDN'T SHOW UP.
GIVEN: sin u = 3/5, 0 < u < pi/2
AND BTW, THAT "PLEASE SHOW ALL STEPS" IS FOR EACH PROBLEM. :)
THANKS. 
MATH 
Reiny
sin 2x  sin x = 0
I assume from the questions, that you are familiar with the common identities.
Also you don't state a domain, so I will asuume 0 ≤ x ≤ 2pi
2sinxcos  sinx = 0
sinx(2cosx  1) = 0
sinx = 0 or cosx = 1/2
from sinx = 0 , x = 0,pi,2pi
from cosx = 1/2, x must be in quadrants I or IV, so x = pi/3 or x = (2pipi/3) = 5pi/3
#2, you should recognize the 3,4,5 triangle and since u is in the first quadrant, cos u = 4/5 and tanu = 3/4
Now use your double angle formulas to find sin 2u etc.
#3
Hint 15º = 45º  30º
so sin15
= sin(4530)
= sin45cos30  cos45sin30
= √2/2(√3/2)  √2/2(1/2) = (√6  √2)/4
always check these with a calculator
now do the cosine and the tangent in a similar way. 
MATH 
Reiny
#4 hint: 195+105 = 300
195  105 = 90 mmmmhhhh!
Respond to this Question
Similar Questions

Calculus
I need to find the exact solutions on the interval [0,2pi) for: 2sin^2(x/2)  3sin(x/2) + 1 = 0 I would start: (2sin(x/2)1)(sin(x/2)1) = 0 sin(x/2)=1/2 and sin(x/2)=1 what's next? 
math
Eliminate the parameter (What does that mean? 
Math
Evaluate *Note  We have to find the exact value of these. That I know to do. For example sin5π/12 will be broken into sin (π/6) + (π/4) So... sin 5π/12 sin (π/6) + (π/4) sin π/6 cos π/4 + cos … 
Maths
Solve for x (exact solutions): sin x  sin 3x + sin 5x = 0 ¦Ð ¡Ü x ¡Ü ¦Ð  Thankyou. I tried find the solutions on my graphics calculator but however, the question is to find the EXACT solution(s) for the equation … 
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 … 
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. 
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 … 
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 … 
math
Determine all the possible values of x where 0 deg is more than or equal to x and x is more or equal to 360 deg such that i'm not sure the solution, please correct it, sin x sec x  3 sin x = 0 the solution: sin x 1/cos x  3 sin x … 
trigonometry
1) Find the exact value of the expression: tan−1(tan(−120651/47π))... How do you find Tan(120651/47pi)?