1. The problem asks to analyze and solve parts related to the conic sections given by the equations:
(1) $9x^2 - 16y^2 - 36x - 32y - 124 = 0$ (a homogeneous line equation)
(2) $\frac{x^2}{5} + \frac{y^2}{1} = 1$ (an ellipse)
(3) Find the coordinates of the ellipse's foci given the axes.
(4) From the parabola equation $3y^2 - 10x - 12y - 18 = 0$, find the length of the ellipse's latus rectum.
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2. **Step 1: Rewrite the first equation in standard form**
Given:
$$9x^2 - 16y^2 - 36x - 32y - 124 = 0$$
Group $x$ and $y$ terms:
$$9x^2 - 36x - 16y^2 - 32y = 124$$
Complete the square for $x$ and $y$:
For $x$:
$$9(x^2 - 4x) = 9[(x^2 - 4x + 4) - 4] = 9(x - 2)^2 - 36$$
For $y$:
$$-16(y^2 + 2y) = -16[(y^2 + 2y + 1) - 1] = -16(y + 1)^2 + 16$$
Rewrite the equation:
$$9(x - 2)^2 - 36 - 16(y + 1)^2 + 16 = 124$$
Simplify constants:
$$9(x - 2)^2 - 16(y + 1)^2 - 20 = 124$$
Add 20 to both sides:
$$9(x - 2)^2 - 16(y + 1)^2 = 144$$
Divide both sides by 144:
$$\frac{(x - 2)^2}{16} - \frac{(y + 1)^2}{9} = 1$$
This is the standard form of a hyperbola centered at $(2, -1)$.
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3. **Step 2: Identify the ellipse center from the second equation**
Given ellipse:
$$\frac{x^2}{5} + \frac{y^2}{1} = 1$$
This ellipse is centered at the origin $(0,0)$ because there are no linear $x$ or $y$ terms.
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4. **Step 3: Find the foci of the ellipse**
For ellipse equation:
$$\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1$$
where $a^2 = 5$ and $b^2 = 1$.
Since $a^2 > b^2$, the major axis is along the $x$-axis.
The focal distance $c$ is given by:
$$c = \sqrt{a^2 - b^2} = \sqrt{5 - 1} = \sqrt{4} = 2$$
So the foci are at:
$$(\pm c, 0) = (\pm 2, 0)$$
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5. **Step 4: Find the coordinates of the ellipse's axes intercepts**
- $x$-intercepts: Set $y=0$ in ellipse equation:
$$\frac{x^2}{5} = 1 \Rightarrow x^2 = 5 \Rightarrow x = \pm \sqrt{5}$$
- $y$-intercepts: Set $x=0$:
$$\frac{y^2}{1} = 1 \Rightarrow y^2 = 1 \Rightarrow y = \pm 1$$
So the ellipse intercepts are at $(\pm \sqrt{5}, 0)$ and $(0, \pm 1)$.
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6. **Step 5: Find the length of the latus rectum of the parabola**
Given parabola:
$$3y^2 - 10x - 12y - 18 = 0$$
Rewrite in standard form:
Group $y$ terms:
$$3y^2 - 12y = 10x + 18$$
Complete the square for $y$:
$$3(y^2 - 4y) = 10x + 18$$
$$3[(y^2 - 4y + 4) - 4] = 10x + 18$$
$$3(y - 2)^2 - 12 = 10x + 18$$
Add 12 to both sides:
$$3(y - 2)^2 = 10x + 30$$
Divide both sides by 10:
$$x = \frac{3}{10}(y - 2)^2 - 3$$
This is a parabola opening rightwards with vertex at $(-3, 2)$.
The standard form for a parabola opening right is:
$$x = a(y - k)^2 + h$$
where $a = \frac{3}{10}$.
The length of the latus rectum $L$ is:
$$L = \frac{1}{|a|} = \frac{1}{3/10} = \frac{10}{3}$$
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**Final answers:**
- (1) The conic is a hyperbola centered at $(2, -1)$ with equation:
$$\frac{(x - 2)^2}{16} - \frac{(y + 1)^2}{9} = 1$$
- (2) The ellipse center is at $(0,0)$.
- (3) The ellipse foci are at $(\pm 2, 0)$.
- (4) The length of the latus rectum of the parabola is $\frac{10}{3}$.
Conic Sections C8Cd32
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