Q. 7 B5.0( 1 Vote )

If A = 30o, verify that :

cos 2A = 1-2 sin2A=2cos2 A – 1

Answer :

Given: A =30o

Now, LHS = cos 2(30o)


cos 60o



Now, RHS = 1- 2sin2 A


1- 2sin2 (30o)






Now, RHS = 2cos2 A – 1


2cos2 (30o) - 1






LHS = RHS


Hence Proved


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