Question

Which of the following expression is equivalent to sin(5x) ?

a. sin(3x) cos(2x) + cos(4x) sin(x)
b. sin(4x) cos(x) - cos(4x) sin(x)
c. sin(3x) sin(2x) + cos(3x) cos(2x)
d. sin(3x) sin(2x) - cos(3x) cos(2x)
e. cos(3x) sin(2x) + sin(3x) cos(2x)

Answer 1

sin(5x)
=sin(3x+2x)
=sin3xcos2x+cos2xsin3x

Answer 2

`Use:\\sin(x+y)=sinxcosy+sinycosx\\-------------------------\\sin5x=sin(3x+2x)=sin3xcos2x+sin2xcos3x\\\\Answer:e)`