Write a function that takes the base and height of a triangle and return its area.
triArea(3, 2) ➞ 3 triArea(5, 4) ➞ 10 triArea(7, 4) ➞ 14 triArea(10, 10) ➞ 50 triArea(12, 11) ➞ 66 triArea(0, 60) ➞ 0