## College Algebra (6th Edition)

$b=\frac{2A}{h}-a$
Area of Trapezoid $A=\frac{1}{2}h (a+b)$ Solving for b $A=\frac{h}{2} (a+b)$ Multiply both sides by $\frac{2}{h}$ $\frac{2}{h} \times A=\frac{2}{h} \times \frac{h}{2} (a+b)$ $\frac{2A}{h} = a+b$ Add $-a$ to both sides $\frac{2A}{h}-a = a+b-a$ $\frac{2A}{h}-a = b$ $b=\frac{2A}{h}-a$