Let P(x1,y1) and Q(x2,y2) be two distinct points on the ellipse x29+ y24=1 such that y1>0, and y2>0. Let C denote the circle x2+y2=9, and M be the point (3,0). Suppose the line x=x1 intersects C at R, and the line x=x2 intersects C at S, such that the y-coordinates of R and S are positive. Let ROM= 6 and SOM= 3, where O denotes the origin (0,0). Let |XY| denote the length of the line segment XY. Then which of the following statements is (are) TRUE?
- The equation of the line joining P and Q is 2x+3y=3(1+ 3)
- The equation of the line joining P and Q is 2x+y=3(1+ 3)
- If N2=(x2,0), then 3|N2Q|=2|N2S|
- If N1=(x1,0), then 9|N1P|=4|N1R|
Answer
(1) The equation of the line joining P and Q is 2x+3y=3(1+ 3), (3) If N2=(x2,0), then 3|N2Q|=2|N2S|
Solution
C is the auxiliary circle, so ROM, SOM are the eccentric angles of P, Q.
P= (3 6,2 6 )= ( 3 32,1 ), R= ( 3 32, 32 ); Q= ( 32, 3 ), S= ( 32, 3 32 ).
Slope PQ= 3-1 32- 3 32=- 23; line: 2x+3y=3 3+3=3(1+ 3) — (A) true, (B) false.
|N2Q|= 3, |N2S|= 3 32: 3 3=2 3 32 — (C) true.
|N1P|=1, |N1R|= 32: 9 6 — (D) false.
Answer: (A), (C)