Question

Prove that :- {(1+cosA)^2 +(1-cosA) ^2} ÷ {sin^2A} = 2 (1+2cot^2A)​

Answer 1

Answer:

I think this question is wroung the RHS must be like 2(1+cosec^2A)

Answer 2

Answer:

Step-by-step explanation:

(a + b)² + (a - b)² = 2(a² + b²)

a = 1 ; b = Cos A

(1 + Cos A)² + (1 - Cos A)² = 2(1² + Cos² A)

                                         = 2(1 +Cos² A)   ----------(I)

LHS = { (1 + Cos A)² + (1 - Cos A)²} ÷ { Sin² A}

      = { 2( 1 + Cos² A )} ÷ Sin² A                  {From (I)}

      = { 2 (Sin² A + Cos² A + Cos² A) } ÷ { Sin² A}    {Here, Sin² A + Cos² A = 1 }

     = 2 (Sin² A + 2Cos² A) }  ÷ { Sin² A}    

     $= 2 ( \frac{Sin^{2} A}{Sin^2 A} + \frac{2Cos^{2} A}{Sin^{2} A})$

      = 2( 1 + 2 Cot²  A) =RHS