If sinB = prove that 3cosB – 4cos3B = 0.

Q9 of 104 Page 188

If sinB = prove that 3cosB – 4cos³B = 0.

Let AC = 1 and AB = 2.

⇒

∴ BC = √3 (by Pythagoras theorem) we know that

⇒

= 0

which is equal to the R.H.S

If tan θ = , find the value of

If sec θ = find the value of

If tanA = √3, verify that

(1) sin²A + cos²A = 1

(2) sec²A – tan²A = 1

(3) 1 + cot²A = cosec²A

If cos θ = , verify that tan²θ – sin²θ = tan²θ⋅ sin²θ