Monday, July 31, 2017

Q.Prove that: [1+Tan^2(pie/4-A)] / [1-Tan^2(pie/4-A)] = cosec2A

Soln:
L.H.S.
= [1 + Tan2(p/4-A)]/[1 – Tan2(p/4-A)]
= 1/[{1 – Tan2(p/4-A)}/{ 1 + Tan2(p/4-A)}]
= 1/[cos2(p/4-A)]                   [Since,  cos2A = (1 – Tan2A)/(1 + Tan2A)]
= 1/[cos(p/2-2A)]
= 1/sin2A
= cosec2A = R.H.S