Question

Given the center and radius of a circle, write the equation of the circle.

Center: (-2, 1)

Radius = 5

Answer 1

Answer:

(x + 2)² + (y - 1)² = 25

General Formulas and Concepts:

Algebra I

• Coordinates (x, y)

Pre-Calc

Circle Center Formula: (x - h)² + (y - k)² = r²

• (h, k) is center
• r is radius

Step-by-step explanation:

Step 1: Define

Identify variables

(h, k) = (-2, 1)

r = 5

Step 2: Find Equation

1. Substitute in variables [Circle Center Formula]:                                             (x - -2)² + (y - 1)² = 5²
2. Simplify:                                                                                                             (x + 2)² + (y - 1)² = 25

Topic: Pre-Calculus

Unit: Conics

Book: Pre-Calculus (McGraw Hill)