Question

The equation of a circle centered at the origin is x2 + y2 = 16. What is the radius of the circle?

A.8
B.16
C.4
D.256

Answer 1

C 4

Explanation:

well 4x2 + 4x2 = 16

and radius is 1/2 of diameter so 1/2 of 8 is 4

Answer 2

The radius of circle is 4

Explanation:

Given as :

The equation of circle is given as :

x² + y² = 16

Now The standard equation of

( x - h )² + ( y - k )² = r²

where h , k are center of circle

r is the radius of circle

From given circle equation x² + y² = 16 can be written as

( x - 0 )² + ( y - 0 )² = (4)²

So, The center of this circle is ( h , k ) = ( 0 , 0 ) And radius of circle = 4

Hence The radius of circle is 4 Answer