Skip to main content
Back to Conic Sections
JEE Main 2023
Conic Sections
Parabola
Easy

Question

A triangle is formed by the tangents at the point (2, 2) on the curves y2=2xy^2=2x and x2+y2=4xx^2+y^2=4x, and the line x+y+2=0x+y+2=0. If rr is the radius of its circumcircle, then r2r^2 is equal to ___________.

Answer: 2

Solution

This problem asks for the square of the circumradius (r2r^2) of a triangle formed by three specific lines. A common strategy for finding the circumradius (RR) of a triangle is to first determine if it's a right-angled triangle. If it is, the circumradius is simply half the length of its hypotenuse. Otherwise, the general formula R=abc4KR = \frac{abc}{4K} (where a,b,ca, b, c are side lengths and KK is the area) is used, or the circumcenter can be found. Given that the expected answer for r2r^2 is a simple integer, a right-angled triangle is a strong possibility, as it significantly simplifies calculations.

Let's break down the solution into clear steps.

Practice More Conic Sections Questions

View All Questions