Edexcel C2 Co-ordinate geometry Question

Please help me with this:
The line PQ is the diameter of the circle, where P and Q are (5, 6) and (-2, 2) respectively. Find the equation of the circle.

Could you show the method where you would find the length of the diameter, then halve it to find the radius, instead of finding the midpoint and the length from the midpoint to one of the points P or Q for the radius.

When i tried it with he first method i got that the lenght of the radius was 5 (finding distance between P and Q and halving)....does anyone know where i went wrong

Reply 1

Hōseki

14

Original post by THESTRESS

Please help me with this:
The line PQ is the diameter of the circle, where P and Q are (5, 6) and (-2, 2) respectively. Find the equation of the circle.

Could you show the method where you would find the length of the diameter, then halve it to find the radius, instead of finding the midpoint and the length from the midpoint to one of the points P or Q for the radius.

When i tried it with he first method i got that the lenght of the radius was 5 (finding distance between P and Q and halving)....does anyone know where i went wrong

First we need to find the midpoint...
For x: (5+-2)/2= 1.5
For y: (6+2)/2= 4
So your midpoint coordinates are 1.5,4

To find r^2: (-2-1.5)^2+(2-4)^2

Then you simply substitute into the circle equation
(x-a)^2+(y-b)^2=r^2

(edited 8 years ago)

Reply 2

Zacken

22

Original post by THESTRESS

When i tried it with he first method i got that the lenght of the radius was 5 (finding distance between P and Q and halving)....does anyone know where i went wrong

Well, you need to show us your working for us to be able to point out what went wrong.

Edexcel C2 Co-ordinate geometry Question

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you