Hobbies And Interests
Perimeter of a Trapezoid
Draw a trapezoid and label the lower base as "B," the upper base as "b," the left side as "a" and the right side as "c." The perimeter of a trapezoid, as it is in other shapes, is merely the distance around the exterior of the shape. The formula for the perimeter is B + b + a + c.
Perimeter Example
Solve the perimeter of a trapezoid with sides of 3 and 2, a lower base of 8 and an upper base of 5. Identify what the data represents: a =3, c = 2, B = 8 and b = 5 (note that the values of "a" and "c" can be switched around). Write out the formula with the data plugged in: 8 + 5 + 3 + 2 = 18.
Area of a Trapezoid
The area of a trapezoid can be found using the formula (1/2)h * (B + b), where "h" is the height, "B" is the lower base and "b" is the upper base. The formula is derived from the area formula for parallelograms: (B + b) * h. What's the relationship between parallelograms and trapezoids? Make a duplicate of the trapezoid and flip it over to fit with the original and the two together form a parallelogram. Since it takes two trapezoids, only half of the parallelogram formula is required.
Area Example
Solve the area of a trapezoid where the lower base is 10, the upper base is 4 and the height is 5. Write out what each number represents: B = 10, b = 4 and h = 5. Plug the data into the formula: (1/2)(10 + 4) = (1/2)(14) or Area = 7.