Question

Sin 35° × sin 55° - cos 35° × cos 55°

Answer 1

Answer:

-  cos 20°

Step-by-step explanation:

N = Sin 35° × sin 55° - cos 35° × cos 55° = - ( coc 35° cos 55° - sin 35° sin55° )

= - cos (   35° - 55°) = - cos -  20°  = -  cos 20°