JEE Main 2015MathematicsTrigonometric Ratios & IdentitiesMediumMCQ

JEE Main 2015 — Trigonometric Ratios & Identities Question with Solution

JEE Main 2015 (10 Apr Online)

Question

In a ΔABC, ab=2+3, and ∠C=60°. Then the ordered pair (∠A,∠B) is equal to:

Choose an option

Show full solutionCorrect option: A
Correct answer
A105°, 15°

Step-by-step explanation

ab>1⇒∠A>∠B

A+B=120°

⇒sin(120°−B)sinB=2+3

⇒  32cotB+12=2+3

⇒ cotB=2332+3

 ⇒cotB=2+3

⇒   B=15°

Hence, (∠A,∠B)=(105°,15°)

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About this question

This is a previous-year question from JEE Main 2015, covering the Trigonometric Ratios & Identities chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.