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SSC CGL 2025 PYQ — Question 54

SSC CGL - 18 Sep 2025 - Shift 1 • Quantitative Aptitude • Q54

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If sin2A - cos2A = 121\over2, find the value of cos2A

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Correct answer: B

Explanation

The correct answer is Option 2 i.e. 141\over4.

sin2A – cos2A = 1/2

⇒ 1 – cos2A – cos2A = 1/2

⇒ 1 – 2cos2A = 1/2

⇒ –2cos2A = –1/2

⇒ 2cos2A = 1/2

⇒ cos2A = 1/4