Question

if sin150 cos120is equals to the

Answer 1

First of all, observe that 150=180−30.

Then, remember that we have

cos(180−x)=−cos(x)
sin(180−x)=sin(x)

Plug in x=30 to get

cos(180−30)=−cos(30)
sin(180−30)=sin(30)

the answer comes from the fact that cos(30)=√32 and sin(30)=12 are known values.