Write the equation in standard form for the circle that has a diameter with endpoints (-5, 9) and (-1, 9).
Options
A
B
C
D
Answer & Analysis
Answer
A
Analysis
Question Analysis
The main focus is to use the endpoints of the diameter of a circle to find its center and radius, and then write the circle's equation in standard form.
Key Concept Explanation
The standard form of a circle's equation is , where is the center of the circle and is the radius. The center of a circle is the mid - point of its diameter. The mid - point formula for two points and is , and the radius is half the length of the diameter. The distance formula between two points and is .
Step - by - Step Solution
1. Find the center of the circle:
Given the endpoints of the diameter and , use the mid - point formula.
and . So, the center of the circle is .
2. Find the radius of the circle:
Use the distance formula to find the length of the diameter. .
The radius .
3. Write the equation of the circle:
Substitute , , and into the standard form
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