If A = 30o, verify that :cos 2A = 1-2 sin2A=2cos2 A – 1

Given: A =30oNow, LHS = cos 2(30o)⇒ cos 60oNow, RHS = 1- 2sin2 A⇒ 1- 2sin2 (30o)Now, RHS = 2cos2 A – 1⇒ 2cos2 (30o) - 1∴ LHS = RHSHence Proved

Q7 of 268 Page 4

If A = 30^o, verify that :
cos 2A = 1-2 sin²A=2cos² A – 1

Given: A =30^o

Now, LHS = cos 2(30^o)

⇒ cos 60^o

Now, RHS = 1- 2sin² A

⇒ 1- 2sin² (30^o)

Now, RHS = 2cos² A – 1

⇒ 2cos² (30^o) - 1

∴ LHS = RHS

Hence Proved

If A=60^o and B = 30^o, verify that :

tan (A – B) =

If A = 30^o, verify that :

sin 2A = 2 sin A cos A

If θ = 30°, verify that :

sin 3θ = 3 sinθ – 4 sin³θ

If θ = 30°, verify that :

cos3θ = 4cos³θ – 3cosθ