Question 145017
To answer this question, you need to know the "area" of the sail.  The area of any triangle is 1/2(base)(height).

The key is that they told you that it is a "right-triangle".  Knowing that, you can apply Pythagorean's theorem to find the length of the base of the sail.


Let x = length of the base of the sail
then
x^2 + 12^2 = 13^2
x^2 + 144 = 169
x^2 = 25
x = 5 feet

Area of sail:
1/2(base)(height)
= 1/2(5)(12)
= 5(6)
= 30 sq ft

At $10 per sq ft then the total cost is:
10 * 30 = $300