Almost the same.
Because DK is in parallel with AC
So BDK angle = 90.
Because isosceles trapezoid
Therefore, AC=BD=BK (it is necessary to prove that the four ACKD are parallel to each other).
Because the trapezoidal area is the BDK area of triangle (triangle with the same base and height)
Do DE perpendicular to BC
Good, good. Keep listening to me.
(Hint: the triangle BDK is an isosceles right triangle) =
Because BK*DE/2=49, it is easy to prove that DE= 1/2BK.
So de squared =49.
DE=7=AF
The first question has been answered.
The second question is the same. Take a closer look. Isn't AD+BC our dear BK? .....
So DE= 1/2BK=5.
I answered the fake first. Don't! oh
I'm online, and you can always ask me for help.