The side length (B) is used to compute the perimeter of the triangle. For the 3-sided triangle, the perimeter is ...
P = 3B = 3·1.73 = 5.19
The "height" (H) measured from the center of the circle to the middle of one side is called the "apothem" (a). The area of the triangle (A) is the product of half that and the perimeter:
A = (1/2)aP = (1/2)·0.5·5.19 = 1.2975 . . . . . . square units
Okay so first we need to find 40% of 7.50. To do this you simply divide the percentage by 100, so you have .4 now. You multiply 7.50 by .4 and get 3. Lastly, you just subtract 3 from 7.50 and you get $4.50
