Area is base x height
12 x 6 = 72
the area is 72 in^2
There is a really easy way to do this problem and that is to use a graphing website
after punching in the functions:
A. depending of whether it is -5/(2x) or (-5/2)x: intersecting but not perpendicular or parallel
B. These two lines are perpendicular
C. Parallel lines
D. intersecting but not perpendicular
The volume of a sphere of radius r is given by

For your given conditions, the volume of 1/2 a sphere becomes

Seems to match your 2nd choice:
... 1 over 24 over 322 over 7(83)
Step-by-step explanation:
6p+7=9
6p=9-7
6p=2
p=2/6
p=1/2