SSC CGL 2020 PYQ — Question 66

SSC CGL - 5th March 2020 Shift 1 • Quantitative Aptitude • Q66

The value of (sec6θ -  tan6θ - 3sec2θ tan2θ + 1)/(cos4θ - sin4θ + 2sin2θ + 2) is:

Show answer & explanation

Correct answer: C

Explanation

The correct answer is option 3 i.e 2/3

Understanding Application
We will use trigonometric identities to simplify the given function.

We know that,

⇒ sec2θ - tan2θ = 1

Raising power to 3 on both sides.

⇒ (sec2θ - tan2θ)3 = 1

⇒ Sec6θ - tan6θ - 3sec2θ × tan2θ(sec2θ - tan2θ) = 1

⇒ sec6θ tan6θ - 3sec2θ tan2θ + 1 = 1 + 1 = 2

Which is numretor of the function.

⇒ cos4θ - sin4θ = (cos2θ - sin2θ)(cos2θ + sin2θ) = cos2θ - sin2θ

⇒ cos2θ - sin2θ = 1 - sin2θ - sin2θ = 1 - 2sin2θ

Our denominator will be as

⇒ cos4θ - sin4θ + 2sin2θ + 2 = 1 - 2sin2θ + 2sin2θ + 2 = 3

The function will be 2/3