Question

PLEASE HELP! Express 2sin3theta sin5theta as an algebraic sum:
a. -cos8theta + cos2theta
b. cos8theta - cos2theta
c. -cos8theta - cos2theta
d. cos8theta + cos2theta

Answer 1

I keep posting the textbook for a reason http://finedrafts.com/files/Larson%20PreCal%208th/Larson_Precalculus_8th_txtbk.pdf

Answer 2

Yea, but for some reason it's not loading :/ I appreciate it though

Answer 3

\[\sin(u ± v) = \sin u \cos v ± \cos u \sin v\]
\[\sin3x=\sin(x +2x) = \sin x \cos 2x + \cos x \sin 2x\]

Answer 4

wait until your computer completely downloads it :)

Answer 5

hate when that happens lol

Answer 6

Thanks @UnkleRhaukus can you please clarify? I got d.

Answer 7

cos8theta + cos2theta is not right,

are a. and d. ment to be the same?

Answer 8

My fault, a. is negative

Answer 9

There, fixed it

Answer 10

which one do you get now?

Answer 11

a.

Answer 12

good stuff

Answer 13

THANKS