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SSC CHSL 2020 PYQ — Question 58

SSC CHSL - 13th October 2020 - Shift 1 • Quantitative Aptitude • Q58

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If 117 Cos2 A + 129 Sin2 A = 120 and 170 Cos2 B + 158 Sin2 B = 161, then the value of Cosec2 A Sec2 B is:

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Correct answer: D

Explanation

The correct answer is option 4 i.e 16

Understanding Application
We will use basic trigonometric identities to find the correct answer.

We have given that

⇒ 117 Cos2 A + 129 Sin2 A = 120

⇒ 117 + 12 Sin2 A = 120

⇒ Sin2 A = 1 / 4

⇒ Cosec2 A = 4

⇒ 170 Cos2 B + 158 Sin2 B = 161

⇒ 158 + 12 Cos2 B = 161

Cos2 B = 1 / 4

Sec2 B = 4

⇒ Cosec2 A Sec2 B 

⇒ 4 × 4 = 16