Question

prove cot2a - 1/ sin2a =-1

Answer 1

1/sin2A=cosec2A=cot2A=cosec24=cot2A-1/sin2A=cot24-coesec2A=cot2A-1-cot2A= -1

Answer 2

Answer:

Step-by-step explanation:

Cot^2a-1/sin^2a

= (cos^2a/sin^2a)-(1/sin^2a) as (cot^2a= cos^2a/sin^2a)

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

= -sin^2a/sin^2a , as (sin^2a+cos^2a= 1) so (cos^2a-1=-sin^2a)

= -1