Circles

Question 1

What is the standard form equation for circles?

Answer 1

(x-h)² + (y-k)² = r²

Question 2

In (x-h)² + (y-k)² = r²

What does the equation say about the circle?

Answer 2

Center is at (h,k). Radius is r.

Question 3

What is the center and radius?

(x-3)² + (y+5)²=9

Answer 3

Center: (3, -5)

Radius: 3

Question 4

Find the center and radius of:

x²+ y² − 12x − 16y + 51 = 0

ALGEBRAICALLY

Answer 4

1. x²+ y² − 12x − 16y + 51 = 0
2. x² - 12x + 36 + y² -16y + 64 = -51 + 36 + 64
3. (x-6)² + (y-8)² =49
4. Center is (6,8). Radius is 7.

Question 5

Relationship between circles and ellipses

Answer 5

Every circle is an ellipse.