Area of a right triangle is 1/2 x height x base
The area of the first triangle is 1/2 x 12 x 15 = 90 square cm.
The area of the other triangle is 90 and one side is 18:
90 = 1/2 x 18 x S
Multiply both sides by 2:
180 = 18 x S
Divide both sides by 18:
S = 180/18
S = 10
The length of the other side is 10 centimeters
