Geometry Trapezoid

Since the trapezoid is orthodiagonal or right, we have $a=\frac{8+12}{2}=10,$ where $a$ is the altitude. Thus, the area is 100.

i suppose you can set B as (0, 0), put the whole thing on a coordinate plane, and solve it that way by setting DC's length as x.

HOPE THIS *hint* HELPED!

Remember, when a trapezoid is orthodiagonal, meaning having a 90 degrees angle; a right trapezoid, the sum of the two bases divided by 2 is the altitude. In this case, we have the two bases as 8 and 12, so $\frac{8+12}{2}=10$ and by using the formula for the area of a trapezoid, we get $\frac{1}{2}*20*10=\boxed{100}.$

Hope this helped!