Question

The equation of a circle is x2+y2=16.

The radius of the circle is______________

Answer 1

4

Explanation:

from the circle equation ( x - h )^2 + ( y - k )^2 = r^2, 16 is the radius squared, so x^2=16

x= 4 x=-4

we reject -4, bc it's negative, and a radius cannot be negative,

r=4

Answer 2

4

Explanation:

the standard equation of a circle will be given in the form of

`(x-x_(1) )^2+(y-y_(1) )^2 = r^2`, where r is the radius and (x1, y1) is the center point of the circle

in this situations r^2 = 16

r = +4 or -4, but since length cannot be negative, r = 4