A circle has a center that falls on the line #y = 11/7x +8 # and passes through # ( 9 ,1 )# and #(8 ,4 )#. What is the equation of the circle?
1 Answer
Explanation:
Finding the center of the circle:
We can say that the center of the circle lies on the point
Since we know two points on the circle, we know that the distances from the center to each of the points will be the same.
Use the distance formula from the center to each of these points and set them equal to one another:
Square both sides and simplify inside the square roots.
Expand.
The
Plug this value of
This gives us
Now, we need to determine our next step. Our final goal is to determine the equation of the circle. The standard form of the equation of the circle is
Where the circle's center is
Since we know the circle's center, we know that
Thus, all we need to do is to find the radius of the circle. (Really, we need to find
Finding the circle's radius:
The radius is the distance from the center to any point on the circle. We can apply the distance formula from
Squaring both sides, so we have
Constructing the equation of the circle:
Using the equation
We have
Slightly simplified:
Graphical check:
Graphed are the circle, the line
graph{((x+175/26)^2+(y+67/26)^2-87965/338)(y-11/7x-8)((x-9)^2+(y-1)^2-.2)((x-8)^2+(y-4)^2-.2)((x+175/26)^2+(y+67/26)^2-.2)=0 [-41.56, 31.5, -21.63, 14.92]}