SSC CHSL 2023 PYQ — Question 70

SSC CHSL - 09 March 2023 - Shift 1 • Quantitative Aptitude • Q70

What is the value of (1+sec2A1+cos2A)(1+sin2A1+cosec2A) \left (\frac{1+sec^2A}{1+cos^2A} \right ) \left (\frac{1+sin^2A}{1+cosec^2A} \right )?

Show answer & explanation

Correct answer: D

Explanation

The correct answer is Option 4 i.e. tan2A.

(1+sec2A1+cos2A)(1+sin2A1+cosec2A) \left (\frac{1+sec^2A}{1+cos^2A} \right ) \left (\frac{1+sin^2A}{1+cosec^2A} \right )

=(1+1cos⁡2A1+cos⁡2A)(1+sin⁡2A1+1sin⁡2A)=\left( \frac{1 + \frac{1}{\cos^2 A}}{1 + \cos^2 A} \right) \left( \frac{1 + \sin^2 A}{1 + \frac{1}{\sin^2 A}} \right)

=(cos⁡2A+1cos⁡2A1+cos⁡2A)(1+sin⁡2Asin⁡2A+1sin⁡2A)= \left( \frac{\frac{\cos^2 A + 1}{\cos^2 A}}{1 + \cos^2 A} \right) \left( \frac{1 + \sin^2 A}{\frac{\sin^2 A + 1}{\sin^2 A}} \right)

=(cos⁡2A+1cos⁡2A(1+cos⁡2A))((1+sin⁡2A)sin⁡2Asin⁡2A+1)= \left( \frac{\cos^2 A + 1}{\cos^2 A (1 + \cos^2 A)} \right) \left( \frac{(1 + \sin^2 A) \sin^2 A}{\sin^2 A + 1} \right)

=(1cos⁡2A)(sin⁡2A1)= \left( \frac{1}{\cos^2 A} \right) \left( \frac{\sin^2 A}{1} \right)

= tan2A