Circle Inequalities Ce6467
1. **Problem Statement:**
Given the circle equation $$(x + h)^2 + (y + k)^2 = r^2$$ with radius $r > 0$, determine which of the statements I. $hk < 0$, II. $h > -r$, and III. $k < r$ are true.
2. **Understanding the center:**
The center of the circle is at $$(-h, -k)$$ because the equation is in the form $$(x - x_0)^2 + (y - y_0)^2 = r^2$$ where $x_0 = -h$ and $y_0 = -k$.
3. **Given graph description:**
- The circle is centered in the first quadrant (positive $x$ and $y$).
- This means $$-h > 0$$ and $$-k > 0$$.
4. **Analyze the signs of $h$ and $k$:**
Since $$-h > 0$$, it follows that $$h < 0$$.
Since $$-k > 0$$, it follows that $$k < 0$$.
5. **Check statement I: $hk < 0$**
Since both $h$ and $k$ are negative, their product $$hk > 0$$ (negative times negative is positive).
Therefore, statement I is **false**.
6. **Check statement II: $h > -r$**
Since $h < 0$ and $r > 0$, consider the inequality:
$$h > -r$$
Because $h$ is negative but greater than $-r$ means $h$ is to the right of $-r$ on the number line.
Since the center $(-h, -k)$ is in the first quadrant, $-h > 0$ so $h < 0$ but must be greater than $-r$ (which is negative).
This is plausible and generally true because the center must be within $r$ units from the origin.
So statement II is **true**.
7. **Check statement III: $k < r$**
Since $k < 0$ and $r > 0$, $k$ is definitely less than $r$.
So statement III is **true**.
8. **Conclusion:**
Only statements II and III are true.
**Final answer:** C. II and III only