Question

Which of the following is the equation of a circle whose center is at the origin and whose radius is 4?

Answer 1

The equation of a circle whose center is at the origin and whose radius r:

x² + y² = r²

r = 4

Answer: x² + y² = 4²

Answer 2

The equation of a circle whose center is at the origin and whose radius r:

x² + y² = r²

r = 4

Answer: x² + y² = 4²