Finding the Perimeter

• Finding the perimeter of a trapezoid is probably one of the easiest elements of working with them. The perimeter is the sum of all the shape's sides. A trapezoid has four sides. Add the length of the sides together to get the perimeter.
  
  

Finding the Area

• Finding the area of a trapezoid is a little more complicated than finding the perimeter. The formula for computing the area of a trapezoid is A=1/2h(B+b) where A is the total area, h is the height of the shape, B is the length of the longer base at the bottom of the shape and b is the shorter base at the top. Input the numbers into the equation and solve. Remember to work within the parentheses first in order to arrive at the correct answer.
  
  

Parallel Lines

• Often when working with trapezoids you will be asked to find the angle of the parallel lines. It helps to remember what lines are parallel on the shape. The parallel lines on a trapezoid include the short and long bases.
  
  

Isosceles Trapezoids

• Isosceles trapezoids are a special kind of trapezoid. They are the same as regular trapezoids in respect to the lines that are parallel. However, the left and right sides are congruent in isosceles trapezoids. This means that the angles on both sides will be equal to the angles opposite them. The measurement of these angles when combined also equals 180 degrees.