JEE Main 2019MathematicsInverse Trigonometric FunctionsMediumMCQ

JEE Main 2019 — Inverse Trigonometric Functions Question with Solution

JEE Main 2019 (09 Jan Shift 1)

Question

If cos-123x+cos-134x=π2 x>34, then x is equal to :

Choose an option

Show full solutionCorrect option: D
Correct answer
D14512

Step-by-step explanation

We have, cos-123x+cos-134x=π2, x>34   ...i

∴ cos-134x=sin-116x2-94x 

Put in equation i we get, 

⇒cos-123x+sin-116x2-94x=π2  ...ii 

We know sin-1x+cos-1x=π2

From equation ii we get, 

⇒23x=16x2-94x

⇒832=16x2-9  ∵ x≠0

⇒16x2=649+9=1459

⇒x2=145144

⇒x=14512

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About this question

This is a previous-year question from JEE Main 2019, covering the Inverse Trigonometric Functions 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.