Question

Use the squared identities to simplify 2sin2x cos2x.
Check below.

Answer 1

A. (1 - cos(4x))/4
B. (1 + 4cos(2x) + cos(4x))/4
C. (1 + cos(4x))/4
D. (1 + 4cos(2x) - cos(4x))/4

Answer 2

I still can't figure it out. Can someone walk me through it?

Answer 3

I'm only guessing B.

Answer 4

2sin2xcos2x=sin4x

Answer 5

Okay, I figured out that part... But how do I apply it do the question?

Answer 6

I'm thinking A or C now!

Answer 7

C x_x Gah, I had to work a bit on that one. I'll work it out for ya, though, haha.

Answer 8

A right?

Answer 9

\[2\sin(2x)\cos(2x) = \sin(4x)\]
\[\sin(4x) = \sin(2x + 2x) \]
\[\sin(2x+2x) = \sin(2x)\cos(2x) + \sin(2x)\cos(2x)\]
\[2*(\frac{ 1-\cos(2x) }{ 2 })(\frac{ 1+\cos(2x) }{ 2 })\]
\[2*(\frac{ 1-\cos ^{2}(2x) }{ 4 }) \]
\[2*(\frac{ 1-\frac{ 1+\cos(4x) }{ 2 } }{ 4 })\]
\[2(\frac{ \frac{ 2-1+\cos(4x) }{ 2} }{ 4 })\]
\[2*(\frac{ 1+\cos(4x) }{ 8 }) = \frac{ 1+\cos(4x) }{ 4 }\]

Answer 10

*kicks trigonometry in the face*

Answer 11

http://prntscr.com/48wqi4

Answer 12

1-cos(4x)
_________
4