Question

what is the area for h=10,b1=12,b2=14 on a trapiziod

Answer 1

use this 1/2(b1 + b2)

Answer 2

or, better, this:

a = h/2 (b1+b2)

Note: a triangle is just a trapezoid with b1 = 0, so a = 1/2 h (0+b2) = 1/2 bh

a rectangle is just a trapezoid with b1=b2, so a = 1/2 h * (b1+b1) = h*b1