Evaluate cos48°cos42°–sin48°sin42°

Asked by Maharanam446 | 22nd Jan, 2020, 01:21: PM

Expert Answer:

cos48°cos42° – sin48°sin42°
cos(90° - 42°)cos(90° - 48°) – sin48°sin42°
= sin48°sin42° - sin48°sin42°               .... cos(90° - θ) = sinθ
= 0 

Answered by Yasmeen Khan | 22nd Jan, 2020, 05:04: PM