Question 11402
You have the correct formula for the area of a trapezoid. So now all you need to do is to plug the given values into the appropriate places in the formula and do the math.

{{{A = (1/2)h(b1+b2)}}}
{{{A = (1/2)(3)(5+7)}}} Simplify.
{{{A = (1/2)(3)(11)}}}
{{{A = (1/2)(33)}}}
{{{A = 16.5}}} square centimeters.