Area of a trapezoid?

Question

Please answer as many as you can.
Why is the area of a trapezoid B1+B2 X H divided by 2?
And how do you know what is the base and what line is the height in a trapezoid?

Answer 1

in a Trapezoid the bases are different lenghts, so you must ad them and divide by 2 to get the average lenght between them. The height is the same length no matter what.

so

((B1 + B2)/2) * H = area of trapezoid.

Answer 2

Mirror the trapezoid to create a parallelogram. The Area of
that parallelogram would be (b1+b2)H. So since the
parallelogram is a double of the trapezoid just the divide the
area by 2. Getting (B1+B2)/2.

The Height is just the line that intersects one of the sides at 90 degrees.

The Bases are the Parallel sides.

Answer 3

in a trapezoid either of the parallel sides is the base (usually people would pick the longer one as the base but it does not matter)

and the height is the distance between the 2 parallel sides

and you equation is a little bit off for the area of a trapezoid

you should have brackets around (b1+b2)

[(B1+B2)*H]/2

why is that the area - see if you can follow the logic in this web site to understand how they arrived at the area formula

http://www.mathleague.com/help/geometry/area.htm#areaofatrapezoid

Answer 4

there are two bases on a trapazoid. You know the lines that are the bases because they are the only two that are parralel to each other. The hieght is just the distance from one base to the other.