Calculating missing lengths with perimeter of polygons

Maths

In this unit pupils learn how to derive and use the formula for the area of a triangle and trapezium. In the future unit, this knowledge is called upon to find the volume of different prisms and area of composite shapes

In this unit, pupils explored the relationship between perimeter and area. In particular, they considered whether a shape can have the same area and perimeter value

Perimeter and area

True of false? Summing the length and width of a rectangle gives a result that is half of the perimeter of the rectangle.

The perimeter of the octagon is 184 cm. What is the length of one side? 

Two line segments are congruent if they are ______

A rectangular garden has a length of 12 meters and a width of 8 meters. What is the perimeter of the garden?

Lucas is planning to build a rectangular flowerbed in the backyard. They want the flowerbed to have a perimeter of 36 m. If the width of the flowerbed is 6 m, what should be the flowerbed length?

Dany has a triangular room. The room has side lengths measuring 7 m, 9 m, and $$x$$ m. The perimeter of the triangular room is 28 m. What is the length of side $$x$$?

flat (2D), closed figure made up of straight line segments

flat (2D), closed figure made up of curved line segments

3D object made up of straight line segments

flat (2D), open figure made up of straight line segments

True or false? All parallelograms are rhombuses.

Calculate the perimeter of the rectangle.

An irregular polygon has the following side lengths: 5 cm, 8 cm, 6 cm, 7 cm, and 9 cm. What is the perimeter of the polygon?

This lesson will be removed by end of Summer Term 2025.

Calculating missing lengths with perimeter of polygons

Lesson outcome

This lesson will be removed by end of Summer Term 2025.