Question

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

Answer 1

cos 60-30=cos60cos30+sin60sin30

√3/2=1/2.√3/2+1/2.√3/2

√3/2=√3/4+√3/4

√3/2=2√3/4

√3/2=√3/2