Straight Line Question 273

Question: Let $ P=(-1,0),Q=(0,0) $ and $ R=(3,3\sqrt{3}) $ be three point. The equation of the bisector of the angle PQR is

Options:

A) $ \frac{\sqrt{3}}{2}x+y=0 $

B) $ x+\sqrt{3y}=0 $

C) $ \sqrt{3}x+y=0 $

D) $ x+\frac{\sqrt{3}}{2}y=0 $

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Answer:

Correct Answer: C

Solution:

  • [c] The coordinates of points P, Q, R are $ (-1,0) $ , $ (0,0) $ , $ (3,3\sqrt{3}) $ , respectively. Slope of QR $ =\frac{y_2-y_1}{x_2-x_1}=\frac{3\sqrt{3}}{3} $

$ \Rightarrow \tan \theta =\sqrt{3} $

$ \Rightarrow \theta =\frac{\pi }{3}\Rightarrow \angle RQX=\frac{\pi }{3} $

$ \therefore \angle RQP=\pi -\frac{\pi }{3}=\frac{2\pi }{3}; $ Let QM bisects the $ \angle PQR, $

$ \therefore $ Slope of the line $ QM=\tan \frac{2\pi }{3}=-\sqrt{3} $

$ \therefore $ Equation of line OM is $ (y-0)=-\sqrt{3}(x-0) $

$ \Rightarrow y=-\sqrt{3}x\Rightarrow \sqrt{3}x+y=0 $