Question

Express as product Cos80°+cos40°​

Answer 1

Answer:

2Cos60*Sin20 = Sin20

Step-by-step explanation:

We know that CosA + CosB = 2Cos(A+B/2)Sin(A-B/2)

Cos80°+ Cos40° = 2Cos (80+40/2)Sin(80-40/2)

                            = 2Cos60*Sin20

                            = Sin20