Question

A circle passes through point (-2, -1) and its center is at (2, -1). Which equation represents the circle?

Answer 1

The choices are missing, but we can solve the problem from the given information

Answer:

The equation which represents the circle is (x - 2)² + (y + 1)² = 16

Step-by-step explanation:

The form of the equation of a circle is (x - h)² + (y - k)² = r², where

• (h , k) are the coordinates of its center
• r is the radius of it

∵ The coordinates of the center of the circle are (2 , -1)

∴ h = 2 and k = -1

The radius of the circle is the segment whose join the center of the circle and any point on the edge of the circle

∵ The circle passes through point (-2 , -1)

∴ The radius of the circle is the distance from the center (2 , -1)

    and the point (-2 , -1)

The y-coordinates of the two points are equal that means the radius is a horizontal segment and its length is the difference between their x-coordinates

∵ r = 2 - (-2)

∴ r = 4

Now let us substitute h, k, and r in the form of the equation of the circle

∵ (x - 2)² + (y - -1)² = (4)²

∴ (x - 2)² + (y + 1)² = 16

The equation which represents the circle is  (x - 2)² + (y + 1)² = 16