The legs of a right-angled triangle are 12 and 15 cm to find the perimeter.

Let us determine how many centimeters the length of the hypotenuse of the specified triangle will express, if from the condition of the problem we know that its first leg is twelve centimeters, and the length of the second is fifteen centimeters:

√ (15 ^ 2 + 12 ^ 2) = √ (225 + 144) = √369 = 3√41.

Let us determine how many centimeters the perimeter of our geometric figure will express in this case:

15 + 12 + 3√41 = 27 + 3√41.

Answer: Under such initial conditions, the perimeter will be 27 + 3√41 cm.