Question

if A=60° and B =30°, verify that cos (A+B)= cos A cos B- sin A sin ​

Answer 1

Step-by-step explanation:

given,

A=60° , B=30

now,

cos(A+B)=cosA.cosB - sinA.sinB

=cos60°. cos30° - sin60° . sin30°

=1/2 . ✓3/2 - ✓3/2 .1/2

=✓3/4 - ✓3/4

= 0