Area Formulas

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Slide 46

Let’s try something new with the parallelogram.

Earlier, you saw that you could use two trapezoids to make a parallelogram.

Let’s try to figure out the formula since we now know the area formula for a parallelogram.

Slide 47

Trapezoid

Slide 48

Trapezoid

Slide 49

Trapezoid

So we see that we are dividing the parallelogram in half. What will that do to the formula?

Slide 50

Trapezoid

So we see that we are dividing the parallelogram in half. What will that do to the formula?

bh

Slide 51

Trapezoid

So we see that we are dividing the parallelogram in half. What will that do to the formula?

bh

2

Slide 52

Trapezoid

But now there is a problem.

What is wrong with the base?

bh

2

Slide 53

Trapezoid

bh

2

So we need to account for the split base, by calling the top base, base 1, and the bottom base, base 2. By adding them together, we get the original base from the parallelogram. The heights are the same, so no problem there.

Slide 54

Trapezoid

(b1 + b2)h

2

So we need to account for the split base, by calling the top base, base 1, and the bottom base, base 2. By adding them together, we get the original base from the parallelogram. The heights are the same, so no problem there.

base 2

base 1

base 1

base 2

Slide 55

Practice!

Trapezoid

11 m

3 m

5 m

Slide 56

Answers

35 m2

Trapezoid

11 m

3 m

5 m

Slide 57

Summary so far .

bh

Slide 58

Summary so far .

bh

Slide 59

Summary so far .

bh

Slide 60

Summary so far .