Question

show that cot a/2 =sin a / 1- cos a​

Answer 1

Step-by-step explanation:

Using formulae : sin 2a = 2sin (a)cos (a)

cos 2a = 1 -2 sin^2 (a)

1 - cos 2a = 2 sin^2 (a)

R.H.S = sin a / 1 - cos a

= [2 sin(a/2) cos( a/2)] / 2 sin^2( a/2)

= [ cos (a /2) / sin (a/2) ]

= cot (a /2)

= L.H.S