Question

A circle is centered at the point (7,1) and passes through the point (8,7). what is the radius

Answer 1

Easy

the radius is the distance from the center to a point on the circle

we are given
center=(7,1)
 a point=(8,7)
find the distance
distance formula
D=$\sqrt{(x2-x1)^2+(y2-y1)^2}$

so the distance between point and center is radius
D=$\sqrt{(8-7)^2+(7-1)^2}$
D=$\sqrt{(1)^2+(6)^2}$
D=$\sqrt{1+36}$
D=√37 units


radius is √37 units