If P is a point on the rectangular hyperbola x2−y2=a2, C is its centre and S and S′ are foci, then SP⋅S′P is equal to
A
2
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
(CP)2
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
C
(CS)2
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
(SS′)2
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution
The correct option is B(CP)2 Let the coordinate of P be (x1,y1)
Focal distances (SP,S′P)=(ex1±a)
Now (SP)(S′P)=(ex1+a)(ex1−a) =e2x21−a2 =2x21−a2 =(x21−a2)+x21 =y21+x21(∵x21−y21=a2⇒x21−a2=y21) =(CP)2