Check the equation of the circle

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In summary, the equations of the given circles are (x-1)^2 + (y-1)^2 = 10 and (x+1)^2 + (y-2)^2 = 20 respectively. The first circle has a center at (-1,2) and an x-intercept of 3, with a radius of sqrt(10). The second circle has a center at (4,-3) and passes through the point (2,1), with a radius of sqrt(20). Both equations are correct and there are no objections.
  • #1
aisha
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check please the equation of the circle

the Center is C(-1,2) and the x intercept is 3

I found the distance between the center and the point to be r^2=10

and the midpoint of the two given points to be (1,1)

therefore my final equation for this circle is

[tex] (x-1)^2 + (y-1)^2 =10 [/tex]

is my answer correct? Any objections? :-p

Another question Equation of a circle with center (4,-3) that passes through the point (2,1)

for this question I got [tex] (x-4)^2 + (y+3)^2 =20 [/tex]

Is this one right?
 
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  • #2
Unfortunately not quite. You don't need to find any midpoint at all: the center is given.

Also I don't like your radius. It should just be the distance between the two given points (which I calculate to be [itex]\sqrt{20}[/itex]).
 
  • #3
Your answer to the second question is correct.
 
  • #4
oops ok I got my new answer to be

[tex] (x+1)^2 + (y-2)^2 = 20 [/tex]

is this correct now can you also check the second question in the first post? :redface:
 
  • #5
Yep, they're both right now. :smile:
 

Related to Check the equation of the circle

1. What is the equation of a circle?

The equation of a circle is (x - h)^2 + (y - k)^2 = r^2, where (h,k) is the center of the circle and r is the radius. This equation is based on the Pythagorean Theorem, where the distance from any point on the circle to the center is equal to the radius.

2. How do you check if an equation represents a circle?

To check if an equation represents a circle, you can compare it to the standard form of a circle equation, (x - h)^2 + (y - k)^2 = r^2. If the equation matches this form, it represents a circle. You can also graph the equation and see if it forms a circular shape.

3. What are the key components of a circle equation?

The key components of a circle equation are the coordinates of the center (h,k) and the radius r. These components determine the size and position of the circle on a coordinate plane.

4. How do you find the center and radius of a circle given its equation?

To find the center and radius of a circle given its equation, you can rearrange the equation into the standard form, (x - h)^2 + (y - k)^2 = r^2, and then compare it to the known form. The coordinates of the center are (h,k) and the radius is √r^2.

5. What is the significance of the center and radius in a circle equation?

The center and radius in a circle equation determine the position and size of the circle. The center represents the point at which the circle is centered, while the radius determines the distance from the center to any point on the circle. These components are important in understanding and graphing circles.

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