use coordinate geometry to show that a circle, with its centre at O(2,1) can be drawn through the points A(5,5) B(6,-2) and C (-2,2)

what is the area of the circle?

do i need to draw or can i calculate?

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- Nov 24th 2009, 03:37 PMdecoy808coordinate geometry circle
use coordinate geometry to show that a circle, with its centre at O(2,1) can be drawn through the points A(5,5) B(6,-2) and C (-2,2)

what is the area of the circle?

do i need to draw or can i calculate? - Nov 24th 2009, 04:35 PMaidan
- Nov 24th 2009, 05:59 PMSoroban
Hello, decoy808!

I believe there is a typo . . .

Quote:

Use coordinate geometry to show that a circle, with its centre at O(2,1)

can be drawn through the points A(5,5), B(6,-2), and C(-2,-2)

What is the area of the circle?

. . That is, the center is equidistant from the three points.

That distance is the radius of the circle.

. . Now you can find the area of the circle, right?

- Nov 25th 2009, 01:05 AMdecoy808
yes there was a type error at c. should be(-2,-2)

i found the distances

pa=5

pb=7

pc=7

a=pi(r^2)

=3.14 x 7^2

=154

is this correct. many thanks - Nov 25th 2009, 10:25 AMbjhoppercoordinate geometry circle
posted by decoy808

It is much easier to plot the points on coordinate paper.You see that B and C are points on different radii.You erect the slope diagram for the corrected C and find a 3,4 5 right triangle so the radius is 5

bjh