KVPY2010MathematicsEllipse
Let P be an arbitrary point on the ellipse x ² a ² + y ² ~b ² -1, a > b >0 . Suppose F ₁ and F ₂ are the foci of the ellipse. The locus of the centroid of the triangle PF ₁ ~F ₂ as P moves on the ellipse is-
Options
- Aa circle
- Ba parabola
- Can ellipse
- Da hyperbola
Correct answer
C. an ellipse
Step-by-step solution
array l P a , b G ( x _ i 3 , y _ i 3 ) F ₁ ( ae , 0) F ₂ (- ae , 0) h = acos +a e - ae 3 ; = 3 ~h a array array l k= b 3 ; = 3 k b ² + ² =1 9 h² a² + 9 k² b² =1 x² (a² / 9 ) + y² (b² / 9 ) =1 (Ellipse) array