Understanding Area Formulas

Area Formulas

Making Sense of Area Problems

All parallelograms can be cut exactly in half by a diagonal
to form two congruent triangles.

To understand this statement you need to define the following mathematical vocabulary:

● Parallelogram
● Diagonal
● Congruent

Multiple Select

Select all the parallelograms!

• A square

• A rectangle

• A rhombus

• A trapezoid

• A triangle

Multiple Choice

What is a parallelogram?

• A quadrilateral

• A four sided figure with equal angles

• A four sided figure with two sets of parallel sides

• A magic spell that geometry teachers use on their students

Multiple Choice

What is a diagonal?

• A line that joins two non-consecutive vertices

• A sloped line

• A straight line

• I don't know, but it's probably illegal

Multiple Choice

Exactly Equal in Shape and Size (measure)

• Congruent

• Equal

• Similar

• Pass

All triangles can be doubled to form a parallelogram.

How does this statement compare with the
previous statement that:

“All parallelograms can be cut exactly in half by a diagonal to
form two congruent triangles.”

The area of
parallelograms and
triangles!

What is the area formula for a parallelogram?

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What is the area of the green parallelogram?

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What is the area of the red parallelogram?

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What is the area of the purple triangle?

Do you see why the area of a triangle is 1/2 the area of a paralellogram?

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What is the are of the triangle?

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What is $\frac{\left(6\cdot18\right)}{2}$

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What is $18\cdot3$

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What is $6\cdot9?$

What property allows me to either half the height first, half the base first, or half the product of the base and height?

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What is the area of a parallelogram with the same base length and height?

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What is the area of the triangle?

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What is the area of the triangle?

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What is the area of the parallelogram?