Question

Prove
that
SinA. COS2A = 1/2sin4A Sec A
​

Answer 1

Answer:

Sec2a - (sin2a [1-2sin2a])/(cos2a[2cos2a -1])

= sec2a - tan2a [1- 2sin2a]/[2cos2a -1]

= sec2a - tan2a [1- sin2a - sin2a]/ [cos2a + cos2a -1]

= sec2a - tan2a [ cos 2a - sin 2a]/[cos2a - sin2a]

= sec2a - tan2a *1

= sec2a - tan2a

= 1

I hope it's clear to you...