Question

given cot a=7/8 Then evaluate (1+Sin a)(1-sin a)/(1+cos a)(1-cos a)

Answer 1

(1+sin a)(1-sin a)/(1-cos a)(1+cos a)
=(1-sin² a)/(1- cos² a)
=cos² a/sin a
=cot² a

given cot a=7/8
:. cot² a= (7/8)²
= 49/64