7.3.48 (Sorry this is late, I didn't have internet)

Yeah sorry about the lateness.

So, #48

This works best with a diagram, so here goes:
B___c____A
-\ ~~~~~~/
--\~~~~~/
-a-\~~~/-b
----\~/
-----C

angle B=58 degrees
a=40
b=36
OK, so there's no way to go through this without dealing with angle C or side C, so I think it's easiest to go with the angle. To do that, you have to find angle A. So, according to the law of sines, sin(58)/36=sin(A)/40, so A=asin(40*sin(58)/36)=70.4 degrees. Therefore angle C=180-70.4-58=51.6 degrees.

So, then draw an altitude from A to a. Call the intersection of the altitude and a point D. Ok, so, to find the length of the altitude (the height of the triangle, just take the sine of angle C and multiply it by the length of a, which should come out to 31.3 feet. Then multiply that by the base, b, which comes out to 1253.9 square feet.

Hurray!