# POLQ 3 | Lesson 4 | Explore (Finding the Equation of a Circle) Solutions

Solutions:

The equation of the circle is $$(x-0)^2+(y-0)^2 = 16$$ where the center of the circle is $$(0,0)$$ and the radius of 4 squared is 16.

One point is at $$(-1, d)$$ . Substituting $$-1$$ in for $$x$$, the equation is

\begin{align}(-1)^2+d^2 &= 16 \\\\ d^2 &= 15 \\\\ d &=\pm \sqrt{15}\end{align}

The point is $$(-1,\sqrt{15})$$ or $$(-1,-\sqrt{15})$$.

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