Question

sin 3x= 3cos^2(x)sinx - sin^3(x)
prove

Answer 1

well, first id wanna split that 3x into parts

Answer 2

sin(2x+x)

then split the results again

Answer 3

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

etc

Answer 4

with any luck it simplifies down to that

Answer 5

it doesnt simplify down to that

Answer 6

what did you end up with?

Answer 7

4sincos^2-sin

Answer 8

sin(x+x)cos(x)+sin(x)cos(x+x)

2sin(x)cos^2(x) + sin(x)cos^2(x)-sin^3(x)

3sin(x)cos^2(x) -sin^3(x)

Answer 9

you sure?

Answer 10

um

Answer 11

nvm u got it right i used ther wrong identity