The center of a circle is at (0,0) and its radius is 5. Does the point (5,-2) lie on the circle?

1 Answer
Jan 18, 2016

No

Explanation:

A circle with center cc and radius rr is the locus (collection) of points which are distance rr from cc. Thus, given rr and cc, we can tell if a point is on the circle by seeing if it is distance rr from cc.

The distance between two points (x_1, y_1)(x1,y1) and (x_2, y_2)(x2,y2) can be calculated as
"distance" = sqrt((x_2-x_1)^2 + (y_2-y_1)^2)distance=(x2x1)2+(y2y1)2
(This formula can be derived using the Pythagorean theorem)

So, the distance between (0, 0)(0,0) and (5, -2)(5,2) is
sqrt((5-0)^2+(-2-0)^2) = sqrt(25+4) = sqrt(29)(50)2+(20)2=25+4=29

As sqrt(29) != 5295 this means that (5, -2)(5,2) does not lie on the given circle.