 Click to Chat

1800-1023-196

+91-120-4616500

CART 0

• 0

MY CART (5)

Use Coupon: CART20 and get 20% off on all online Study Material

ITEM
DETAILS
MRP
DISCOUNT
FINAL PRICE
Total Price: Rs.

There are no items in this cart.
Continue Shopping

If the normal subtends a right angle at the focus of the parabola y2=8x then its length is...?

a)2√5  b)10√5  c)5√5  d)4√5
2 years ago

let S=(2,0) be focus of the given parabola
Let P(at12,2at1) and Q(at22,2at2) be the points at which the normal intersects the parabola
slope of SP=4t1/2(t12-1)=2t1/t12-1
similarly,slope of SQ=2t2/t22-1
product of slopes=-1
(2t1)(2t2)/(t12-1)(t22-1)=-1
t12t22+t12+t22+1+4t1t2=0
t12t22+2t1t2+1=t12+t22-2t1t2
(t1t2+1)=t1-t2
t1t2+r2=t1-1
t2(t1+1)=t1-1
t2=t1-1/t1+1
-t1-2/t1=t1-1/t1+1
on solving t1=-2
t2=-t1-2/t1
t2=3
P=(8,-8) ; Q=(18,12)
PQ2=(18-8)2+(12-(-8))2=100+400=500
PQ=10(5)1/2
one year ago
Think You Can Provide A Better Answer ?
Answer & Earn Cool Goodies

Other Related Questions on IIT JEE Entrance Exam

View all Questions »  Course Features

• 731 Video Lectures
• Revision Notes
• Previous Year Papers
• Mind Map
• Study Planner
• NCERT Solutions
• Discussion Forum
• Test paper with Video Solution  Course Features

• 731 Video Lectures
• Revision Notes
• Test paper with Video Solution
• Mind Map
• Study Planner
• NCERT Solutions
• Discussion Forum
• Previous Year Exam Questions