Google Classroom
GeoGebraGeoGebra Classroom

Area of triangles and parallelograms

Area

Area is the space enclosed a given object.

Review

Review

What is the area formula of a rectangle?

What is the area of this rectangle?

Image

What would be the area of Triangle ABC?

How does it compare to the area of the rectangle? Create a formula for the area of a triangle.

Figures A, B, and C are parallelograms. Figures D, E, and F are not parallelograms.

Figures A, B, and C are parallelograms. Figures D, E, and F are not parallelograms.

Study the figures above.

How many sides does a parallelogram have?

Do you notice anything about opposite angles of a parallelogram? If so, describe.

Do you notice anything about opposite sides of a parallelogram? If so, describe.

An empty parallelogram is shown on the left. Use any 1 or more of the colored polygons to help find its area.

What is the area of the parallelogram above? Explain your reasoning.

Change the parallelogram by dragging the green points at its vertices. Then use any 1 or more of the colored polygons to help find its area.

What is the area of your parallelogram now? Explain your reasoning.

If you used the polygons on the side, how were they helpful? If you did not, try using one or more of the polygons to show another way to find the area of the parallelogram in the app above. 

Use the parallelograms shown in A and B to help answer the questions below.

Use the parallelograms shown in A and B to help answer the questions below.

What is the area of parallelogram A? Explain your thought process.

What is the area of parallelogram B? Explain your reasoning.

Challenge Question, refer to parallelogram C shown here.

Challenge Question, refer to parallelogram C shown here.

What is the area of parallelogram C? Explain how you know.