Pls tell how that step is coming cot theta step please solve step by step example 14

Pls tell how that step is coming cot theta step please solve step by step example 14 and tan n
tan
of which holds true.
we
1 *tan30cosecO
- 1+tan20
(I + tan2 9)3/2
(2-+3/2
tan; 020fora1104 12—1 SO z —l
tan 2
Since LHSof tan 3 0 e —(2 — 42) 3/2 is real for all O GR. So. RHSrnust
2-a2 20 — a2-2s0± -Jis ass'
From (i) and (ii), we find that the given relation holds true for all a I , II.
EXAMPLE 15 0
We have,