Question

A=60 B=30
cos(a-b)=cos a cos b + sin a sin b

Answer 1

Answer: 1

Step-by-step explanation:

a=60 b=30

l.h.s

sin(a+b)=sin(60+30)

sin 90=1

r.h.s

sin a cos b + cos a sin b

sin 60 cos 30 + cos 60 sin 30

root 3/2 * root 3/2 + 1/2 *1/2

3/4 +1/4

4/4

=1

l.h.s =r.h.s

hence proved...