About 7.99 seconds, the way I figured it out was I did 1022 divided by 16 so that is could be easier to solve, which equals 63.875, when I took the square root of 63.875 I got 7.99.
The formula for a trapezoid is a=a+b/2 x h so plug that back into the equation and you get 15=10/2 *h 15=5*h from here, you know that 15/5 equals 3 and therefore the height of the trapezoid is 3.