Posted by Alex on Tuesday, November 27, 2007 at 11:17pm.
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/2)sin^2(π/4x/2)
= cos^2(π/4x/2)sin^2(π/4x/2)
I got all the way up to cos (π/4  x/2 + π/4  x/2)
The answer is supposed to be sin x. I have no clue how they got that.

Math 2nd question  Reiny, Tuesday, November 27, 2007 at 11:38pm
g) 8sin^2x4
= 4(2sin^2 x  1)
= 4(cos 2x)
= 4cos 2x
h) 12sin^2 (π/4x/2)
= cos 2(π/4x/2)
= cos (π/2x)
= cos(π/2)cosx + sin(π/2)sinx
= 0(sinx) + 1(sinx)
= sinx

Math 2nd question  Reiny, Wednesday, November 28, 2007 at 1:26am
"But can you please explain how you got 4(2sin^2 x  1)"
I took out a common factor of 4
"..and cos 2(π/4x/2) for h"
Ok, let's work it in reverse.
You know that cos 2A = cos^2 A  sin^2 A, or cos 2A = 1  2sin^2 A ,right?
so I simply let A = (π/4x/2)
then 2A = 2(π/4x/2)
= π/2  x
Answer This Question
Related Questions
 MATH  1.)Find the exact solution algebriacally, if possible: (PLEASE SHOW ALL ...
 Algebra2  1. An artist is designing triangular mirrors. Determine the number...
 Algebra 2 ..  1. An artist is designing triangular mirrors. Determine the ...
 Algebra 2....  1. An artist is designing triangular mirrors. Determine the ...
 trig  A coil of wire rotating in a magnetic field induces a coltage E=20sin((...
 advanced functions  Use the Pythagorean identity to show that the double angle ...
 precalculus  write each expression as the sine, cosine or tangent of a double ...
 math  Which statement is ALWAYS true? A) The sine of an angle is equal to the ...
 trig  The terminal side of an angle includes the point (5,12). Give the sine, ...
 PreCalculus  I really need help on this question Simplify the expression by ...
More Related Questions