The radius of a circle around a regular triangle is 3 cm. Find the side of the triangle.

A regular (or equilateral) triangle is a triangle in which the lengths of all sides are equal to each other, and the degree measures of all angles are equal (60 ° each).
The length of the radius of a circle circumscribed about an equilateral triangle is found by the formula:
R = (a√3) / 3,
where a is the length of the side of the triangle.
By condition, the length of the radius of the circumscribed circle is 3 cm. Substitute this value into the formula:
(a√3) / 3 = 3;
a = (3 * 3) / √3 (proportional);
a = 9 / √3;
a = (9 * √3) / (√3 * √3);
a = 9√3 / 3;
a = 3√3 cm.
Answer: 3√3 cm.