An equilateral triangle has a side length of 12 centimeters. What is the measure, in centimeters, of its altitude?

Altitude forms a 30-60-90 (or 1-sqrt (3) - 2) triangle. The hypotenuse is the equilateral triangle's side length, 12 centimeters. The altitude is the sqrt (3) side. 12 / sqrt (3) = 6sqrt (3). Therefore the altitude of the triangle is 6 * sqrt (3) centimeters.