Write down the equation of a circle centered at C (0; 69), R = 7.

We use the formula describing the equation of the circle:

(x – x0) ² + (y – y0) ² = R²;

This formula uses data:

x0 – abscissa of the center of the circle;

y0 – ordinate of the center of the circle;

R is the size of the radius of the circle.

By condition, the center of the circle is at the point C (0, 69), or: x0 = 0, y0 = 69. The radius of this circle, R = 7.

Substituting these tasks into the main formula, we get the following:

(x – 0) ² + (y – 69) ² = 7²;

x² + (y – 69) ² = 49.

This is the desired equation of the circle.