SSC CGL 2016 PYQ — Question 13

SSC CGL Tier II Quant - 30/11/2016 • Quantitative Aptitude • Q13

If a2sec2x - b2tan2x = c2 then, find the the value of sec2x + tan2x. (b2 ≠ a2) :

Show answer & explanation

Correct answer: B

Explanation

The correct answer is Option 2 i.e. (b2 + a2 - 2c2)/(b2 - a2).

a2sec2x - b2tan2x = c2 .....(1)

we know, 

⇒ sec2x - tan2x = 1

⇒ tan2x = sec2x - 1  .....(2)

From (1) and (2), we get

⇒ sec2x = (c2 - b2)/(a2 - b2)

⇒ tan2x = (c2 - a2)/(a2 - b2)

⇒ sec2x + tan2x = (c2 - b2 + c2 - a2)/(a2 - b2) = (b2 + a2 - 2c2)/(b2 - a2)