If θ = 30°, verify that :sin 3θ = 3 sinθ – 4 sin3θ

Given: θ =30oNow, LHS = sin 3(30o)⇒ sin 90o= 1Now, RHS = 3 sin θ - 4 sin3 θ⇒ 3 sin (30o) - 4 sin3 (30o)= 1∴ LHS = RHSHence Proved

Q8 of 268 Page 4

If θ = 30°, verify that :
sin 3θ = 3 sinθ – 4 sin³θ

Given: θ =30^o

Now, LHS = sin 3(30^o)

⇒ sin 90^o

= 1

Now, RHS = 3 sin θ - 4 sin³ θ

⇒ 3 sin (30^o) - 4 sin³ (30^o)

= 1

∴ LHS = RHS

Hence Proved

If A = 30^o, verify that :

sin 2A = 2 sin A cos A

If A = 30^o, verify that :

cos 2A = 1-2 sin²A=2cos² A – 1

If θ = 30°, verify that :

cos3θ = 4cos³θ – 3cosθ

If sin (A + B) = 1 and cos (A – B) = , then find A and B.