The equation of a circle with diameters are 2x - 3y + 12 = 0 and x + 4y - 5 = 0 and area of 154 sq. units is
x 2+ y 2 + 6x - 4y - 36 = 0
This problem requires finding the equation of a circle given information about its diameters and area. The key steps involve finding the circle's center by intersecting the diameter lines and determining the radius from the given area.
The center of the circle is the point where the two given diameters intersect. We need to solve the system of linear equations:
To solve this system, we can use substitution or elimination. Let's use elimination:
$$(2x + 8y - 10) - (2x - 3y + 12) = 0$$ $$2x + 8y - 10 - 2x + 3y - 12 = 0$$ $$(8y + 3y) + (-10 - 12) = 0$$ $$11y - 22 = 0$$ $$11y = 22$$ $$y = \frac{22}{11}$$ $$y = 2$$
Therefore, the center of the circle, $(h, k)$, is $(-3, 2)$.
The area of the circle is given as 154 square units. The formula for the area ($A$) of a circle with radius ($r$) is $A = \pi r^2$. We can use the approximation $\pi \approx \frac{22}{7}$.
$$A = \pi r^2$$
$$154 = \frac{22}{7} r^2$$
To find $r^2$, rearrange the equation:
$$r^2 = \frac{154 \times 7}{22}$$
Simplify the fraction:
$$r^2 = \frac{(7 \times 22) \times 7}{22}$$
$$r^2 = 7 \times 7$$
$$r^2 = 49$$
So, the radius squared ($r^2$) is 49.
The standard equation of a circle with center $(h, k)$ and radius $r$ is:
$$(x - h)^2 + (y - k)^2 = r^2$$
Substitute the center $(h, k) = (-3, 2)$ and $r^2 = 49$ into the standard equation:
$$(x - (-3))^2 + (y - 2)^2 = 49$$
$$(x + 3)^2 + (y - 2)^2 = 49$$
Now, expand the squared terms:
$$(x^2 + 2 \cdot x \cdot 3 + 3^2) + (y^2 - 2 \cdot y \cdot 2 + 2^2) = 49$$
$$(x^2 + 6x + 9) + (y^2 - 4y + 4) = 49$$
Combine the terms:
$$x^2 + y^2 + 6x - 4y + 9 + 4 = 49$$
$$x^2 + y^2 + 6x - 4y + 13 = 49$$
Move the constant term to the left side:
$$x^2 + y^2 + 6x - 4y + 13 - 49 = 0$$
$$x^2 + y^2 + 6x - 4y - 36 = 0$$
The derived equation of the circle is $x^2 + y^2 + 6x - 4y - 36 = 0$. Let's compare this with the given options:
The derived equation matches Option 1.
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