Question

give the answer fast​

Answer 1

Answer:

. Sin780°.Sin120°+Cos240°.Sin390°=12

Taking LHS

Sin780°.Sin120°+Cos240°.Sin390°

=> Sin(2×360°+60°).Sin(180°−60°)+Cos(180°+60°).Sin(360°+30°)

=>Sin(4π+60°).Sin(π−60°)+Cos(π+60°).Sin(2π+30°)

=> Sin60°.Sin60°−Cos60°.Sin30°

=> 3√2.3√2−12.12=34−14

=> 24=12=RHS

Hence Proved