By Ajay Kumar

Verified by Ajay Kumar

Mock Test →

In a right triangle ABC, right-angled at B, if \(\tan A=1\), what is the value of \(2\sin A\cos A\)?

  1. 2

  2. 5

  3. 6

  4. 1

Answer: D

Solution

Given \(\tan A=1\), so \(A=45^\circ\) because A is an acute angle in a right triangle. Thus, \(\sin A=\frac1{\sqrt2}\) and \(\cos A=\frac1{\sqrt2}\). Therefore, \(2\sin A\cos A=2\times\frac1{\sqrt2}\times\frac1{\sqrt2}=1\). Trick: Use \(2\sin A\cos A=\sin2A=\sin90^\circ=1\).

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