A few days ago
gordonfreak

Calc problem, prove this please?

prove sin4x/sinx = 4cosxcos2x

show all work please.

your help is greatly appreciated.

Top 1 Answers
A few days ago
Anonymous

Favorite Answer

sin(4x)

= sin(2 * (2x) )

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

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

= 4sin(x)cos(x)cos(2x).

Dividing by sin(x):

sin(4x) / sin(x) = 4cos(x)cos(2x).

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