Question

Cos(π/12)+cos(3π/12)+cos(9π/12)+cos(11π/12)=0

Answer 1

Step-by-step explanation:

cos(π/12) + cos(11π/12) + cos(3π/12) + cos(9π/12)

= cos(π/12) + cos(π-π/12) + cos(3π/12) + cos(π-3π/12)

= in second quadrant value of cos is negative

=cosπ/12 - cosπ/12 + cos3π/12 - cos3π/12

=0

Answer 2

Answer:

Question is wrong First two terms are cot and not cos

$cot \binom{\pi}{12} + \cot \binom{3\pi}{12} + \cos\binom{9\pi}{12} + \cos\binom{11\pi}{12} )$