Question
Question: Let AB be a chord of the circle x<sup>2</sup> + y<sup>2</sup> = r<sup>2</sup> subtending a right ang...
Let AB be a chord of the circle x2 + y2 = r2 subtending a right angle at the centre, then the locus of the centroid of the triangle PAB as P moves on the circle is
A
A parabola
B
A circle
C
An ellipse
D
None
Answer
A circle
Explanation
Solution
Centroid
x = 
, y = 
3x – r = r cos q
3y – r = r sin q
(3x –r)2 + (3y –r)2 = r2
which is circle.