Find the radius of the circle if its diameter is 45 cm?

First of all, to solve this problem, we need to remember which formula connects the radius and diameter of a circle:

D = 2 * R,

where D is the diameter of the circle;
R is the radius of the circle.

Then, based on this formula, we can express the value of the radius of the circle:

R = D: 2.

Let’s use this formula and calculate what the radius of the circle is:

R = D: 2 = 45: 2 = 22.5 (cm).

Note also that to solve this problem we do not need constant P.

Answer: the radius of the circle is 22.5 cm.