Trigonometry
posted by Kim .
A painter needs to cover a triangular region 62 meters by 68 meters by 70 meters. A can of paint covers 70 square meters. How many cans will be needed?

Let s be half the sum of the three sides (100 m, in this case). If a, b and c are the side lengths of the triangle, the area is
sqrt[s(sa)(sb)(sc)]
= sqrt[100*38*32*30] = 1910 m^2
1910/70 = 27.3 cans are needed