How do i derive the area of a trapezoid?

The area of a trapezoid is:
A= 1/2 (b1 +b2)h

Area equals half the sum of the 2 bases times the height.

“exterior angles of triangles. an exterior (or external) angle is the angle between one side of a triangle and the extension of an adjacent side. try this drag the orange dots on any vertex to reshape the triangle.” look to get to the answer i explained what it means and other things i hope it you .