A circle centered at the origin has a radius of (1)/(2) What is the equation of the cirde? A. x^2+y^2=(1)/(4) B. x^2+y^2=(1)/(2) C. x^2+y^2=1 D. x^2+y^2=2

The equation of a circle with center at the origin is given by $x^2 + y^2 = r^2$, where $r$ is the radius of the circle. In this case, the radius is $\frac{1}{2 so the equation of the circle is $x^2 + y^2 = \left(\frac{1}{2}\right)^2 = \frac{1}{4}$. Therefore, the correct answer is A. $x^{2}+y^{2}=\frac {1}{4}$.