Question

Use the Addition Formula for Sine to prove the Double-Angle Formula for Sine.

sin 2x = 2 sin(x) cos(x)

Rewrite 2x as x + x, and use the Addition Formula for Sine to simplify.

sin 2x= sin(x + x)

I have sin (x) cos(x) + cos (x) sin(x). I can't figure out what it EQUALS to.

Answer 1

it equals 2sin(x)cos(x)

Answer 2

\[\large \sin(x)\cos(x) + \cos(x)\sin(x) = 2\sin(x)\cos(x)\]

Answer 3

Use an appropriate Half-Angle Formula to find the exact value of the expression.
cos 112.5°