How to find the equation of a circle - High School Math
Card 0 of 2
Question
The center of a circle is 
and its radius is 
. Which of the following could be the equation of the circle?
The center of a circle is
Answer
The general equation of a circle is 
, where the center of the circle is 
and the radius is 
.
Thus, we plug the values given into the above equation to get 
.
The general equation of a circle is
Thus, we plug the values given into the above equation to get
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Question
Which one of these equations accurately describes a circle with a center of 
and a radius of 
?
Which one of these equations accurately describes a circle with a center of
Answer
The standard formula for a circle is 
, with 
the center of the circle and 
the radius.
Plug in our given information.
This describes what we are looking for. This equation is not one of the answer choices, however, so subtract 
from both sides.
The standard formula for a circle is
Plug in our given information.
This describes what we are looking for. This equation is not one of the answer choices, however, so subtract
Compare your answer with the correct one above
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