# Hard SAT Math Question 19 — Video Explanation | 1600.now

Source: https://1600.now/hard/19

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19

A circle in the $xy$-plane has a radius of $13$ and has its center at $(-4,\ 9)$. The equation of this circle is $x^2 + y^2 + ax + by + c = 0$, where $a$, $b$, and $c$ are constants. What is the value of $c$?