The center of the circle is (-1 , 0) and the radius is 9 units
Step-by-step explanation:
The standard form of the equation of the circle is
(x - h)² + (y - k)² = r², where
- (h, k) are the coordinates of its center
- r is its radius
This form of the equation is helpful, because you can easily find
the center and the radius.
Now let us solve the problem
∵ The equation is (x + 1)² + y² = 81
- By comparing the two equations
∵ (x - h)² + (y - k)² = r² and (x + 1)² + y² = 81
∴ x - h = x + 1
- Subtract x from both sides
∴ -h = 1
- Divide both sides by -1
∴ h = -1
∵ y - k = y
- Subtract y from both sides
∴ -k = 0
∴ k = 0
∵ h and k are the coordinates of the center of the circle
∴ The center of the circle is (-1 , 0)
∵ r² = 81
- Take √ for both sides
∴ r = 9
∴ The radius is 9 units
The center of the circle is (-1 , 0) and the radius is 9 units
Learn more:
You can learn more about the equation of the circle in brainly.com/question/1952668
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