1. **State the problem:** We need to find the value of $c$ in the equation of a circle given by
$$x^2 + y^2 + ax + by + c = 0,$$
where the circle has center $(-5, 2)$ and radius $9$.
2. **Recall the standard form of a circle's equation:**
$$(x - h)^2 + (y - k)^2 = r^2,$$
where $(h, k)$ is the center and $r$ is the radius.
3. **Write the given circle's equation in standard form:**
$$(x + 5)^2 + (y - 2)^2 = 9^2 = 81.$$
4. **Expand the squared terms:**
$$x^2 + 2 \cdot 5 \cdot x + 5^2 + y^2 - 2 \cdot 2 \cdot y + 2^2 = 81,$$
which simplifies to
$$x^2 + 10x + 25 + y^2 - 4y + 4 = 81.$$
5. **Combine like terms and rearrange to the general form:**
$$x^2 + y^2 + 10x - 4y + (25 + 4 - 81) = 0,$$
$$x^2 + y^2 + 10x - 4y - 52 = 0.$$
6. **Identify the constants:** Comparing with
$$x^2 + y^2 + ax + by + c = 0,$$
we have $a = 10$, $b = -4$, and $c = -52$.
**Final answer:**
$$c = -52.$$
Circle Constant C
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