19. Find the equation of a circle whose center is at the origin and radius is 4 .
19.
A. $x^{2}+y^{2}=4$
B. $x^{2}+y^{2}=16$
C. $(x-4)^{2}+(y-4)^{2}=16$
D. $4 x+4 y=16$

Answer

Expert–verified

Hide Steps

Answer

$\boxed{x^{2}+y^{2}=16}$

Steps

Step 1 ：Given center (0,0) and radius 4, the equation of the circle is $(x-0)^{2}+(y-0)^{2}=4^{2}$

Step 2 ：Simplifying, we get $x^{2}+y^{2}=16$ as the equation of the circle.

Step 3 ：$\boxed{x^{2}+y^{2}=16}$