Question

evaluate 4cos^2(17π/6)​

Answer 1

answer:

4cos^2(17π/6)

=4cos^2(3π-π/6)

=4cos^2(-π/6) (as cos(-x) = cosx)

=4cos^2(π/6)

=4(√3/2)^2

=4×3/4

=3

hence, answer is 3.