Question

Cos(60+30)=cos60cos30-sin60sin30

Answer 1

Step-by-step explanation:

we know

cos(A+B)=cosAcosB-sinAsinB

so,cos(60+30)=cos60cos30-sin60sin30

=1/2×√3/2-√3/2×1/2.

=√3/4-√3/4

cos90=0