Question

Cos(70° )cos(20° )+sin(70° )sin(20° )=cos(___°)?

Answer 1

Explanation:

Sum and Difference Formula

cos( U +/- V ) = cosU*cosV -/+ sinU*sinV

cos( U - V ) = cos(70)cos(20) + sin(70)sin(20)

cos( U - V ) = cos (70 - 20)

cos( 50 ) = .642788