Question

Cos 170×cos 150×cos 130 ×cos 110 evalute

Answer 1

cos 170*cos150*cos130*cos110=0.188

Answer 2

Answer:

A=cos(180-10).cos(180-30).cos (180-50).cos (180-70)

A=cos10°×cos 30°×cos 50°×cos 70°

A=cos10°×cos(60-10)×cos(60+10)cos30°

cosalpha×cos(60-alpha)×cos(60+alpha)=1/4cos3alpha

divided by alpha=10

=1/4cos30°-cos30°=1/4(squareroot3/2)

=3/4×4

=3/16

Hope this helped you