To Prove:

Formula Used:

Proof:

LHS … (1)

Let

Therefore … (2)

From the figure,

… (3)

From (2) and (3),

… (3)

Now, let

Therefore … (4)

From the figure,

… (5)

From (4) and (5),

… (6)

Substituting (3) and (6) in (1), we get

LHS

= RHS

Therefore, LHS = RHS

Hence proved.