1. **State the problem:** We have a circle given by the equation $$x^2 + y^2 + 6x - 2y - 26 = 0$$ and a line $$y = kx - 5$$. We want to find the values of the constant $k$ such that the line intersects the circle at two distinct points.
2. **Rewrite the circle equation in standard form:** Complete the square for $x$ and $y$.
For $x$: $$x^2 + 6x = x^2 + 6x + 9 - 9 = (x+3)^2 - 9$$
For $y$: $$y^2 - 2y = y^2 - 2y + 1 - 1 = (y-1)^2 - 1$$
Substitute back:
$$ (x+3)^2 - 9 + (y-1)^2 - 1 - 26 = 0 $$
$$ (x+3)^2 + (y-1)^2 - 36 = 0 $$
$$ (x+3)^2 + (y-1)^2 = 36 $$
This is a circle with center $(-3,1)$ and radius $6$.
3. **Substitute the line equation into the circle:** Replace $y$ by $kx - 5$ in the circle equation:
$$ (x+3)^2 + (kx - 5 - 1)^2 = 36 $$
$$ (x+3)^2 + (kx - 6)^2 = 36 $$
Expand:
$$ (x+3)^2 = x^2 + 6x + 9 $$
$$ (kx - 6)^2 = k^2 x^2 - 12kx + 36 $$
Sum:
$$ x^2 + 6x + 9 + k^2 x^2 - 12kx + 36 = 36 $$
Simplify:
$$ x^2 + k^2 x^2 + 6x - 12kx + 9 + 36 - 36 = 0 $$
$$ (1 + k^2) x^2 + (6 - 12k) x + 9 = 0 $$
4. **Condition for two distinct intersection points:** The quadratic in $x$ must have two distinct real roots, so its discriminant $\Delta$ must be positive:
$$ \Delta = b^2 - 4ac > 0 $$
where
$$ a = 1 + k^2, \quad b = 6 - 12k, \quad c = 9 $$
Calculate:
$$ \Delta = (6 - 12k)^2 - 4(1 + k^2)(9) $$
$$ = 36 - 144k + 144k^2 - 36 - 36k^2 $$
$$ = 144k^2 - 36k^2 - 144k + 36 - 36 $$
$$ = 108k^2 - 144k $$
5. **Solve inequality:**
$$ 108k^2 - 144k > 0 $$
Divide both sides by 12:
$$ 9k^2 - 12k > 0 $$
Factor:
$$ 3k(3k - 4) > 0 $$
6. **Analyze sign:**
The product $3k(3k - 4)$ is positive when both factors are positive or both are negative.
- Case 1: $3k > 0$ and $3k - 4 > 0$ \Rightarrow $k > 0$ and $k > \frac{4}{3}$ \Rightarrow $k > \frac{4}{3}$
- Case 2: $3k < 0$ and $3k - 4 < 0$ \Rightarrow $k < 0$ and $k < \frac{4}{3}$ (always true) \Rightarrow $k < 0$
7. **Final answer:**
$$ \boxed{k < 0 \text{ or } k > \frac{4}{3}} $$
These are the values of $k$ for which the line intersects the circle at two distinct points.
Circle Line Intersection D5F181
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