The distance from the end of the diameter to the point of the circle is 12 cm.

The distance from the end of the diameter to the point of the circle is 12 cm. And from the other end to the point of the circle is 9 cm. Find the diameter

From the condition, we know that the distance from the end of the diameter to the point of the circle is 12 cm, and from the other end to the point of the circle is 9 cm. And we need to find the diameter of the circle.

Let’s start the solution by remembering that if two chords going out from one point on a circle to the ends of its diameter form a right-angled triangle with it.

So, in order to find the diameter, we will apply the Pythagorean theorem to find the unknown hypotenuse:

c ^ 2 = a ^ 2 + b ^ 2;

c = √ (12 ^ 2 + 9 ^ 2) = √ (144 + 81) = √225 = 15 cm diameter.

R = d / 2 = 15/2 = 7.5 cm.