Answer:
That is a 30 60 90 triangle.
In such a triangle the "middle" size = short side * sq root (3)
height = 5 * sq root (3) = 8.6602540378
Area = (1/2) * 5 * 8.6602540378
Area = 2.5 * 8.6602540378
Area = 21.6506350946 square centimeters
Explanation: