Cos80°×cos60°×cos40°×cos20°
Answers
Answered by
5
Cos80°×cos60°×cos40°×cos20
cos 20 × cos 40 × cos 80 ×1/2
1/4×cos(3×20° ) ×1/2
1/4×cos60°×1/2
1/4×1/2×1/2
1/16
cosa×cos2a ×cos4a = 1/4cos3a
cos 20 × cos 40 × cos 80 ×1/2
1/4×cos(3×20° ) ×1/2
1/4×cos60°×1/2
1/4×1/2×1/2
1/16
cosa×cos2a ×cos4a = 1/4cos3a
Similar questions