Given that the formula for a trapezoid that relates the area A, the two bases, a and b, and the height, h is given by:
[tex]A= \frac{h(a+b)}{2} [/tex]
To solve for b, first multiply both sides by 2 to get:
2A = h(a + b) = ah + bh
Next, subtract ah from both sides to get:
2A - ah = bh
Next, divide both sides by h, to get:
[tex] \frac{(2A-ah)}{h} =b \\ \\ \therefore b=\frac{2A-ah}{h}[/tex]