15.1 Perimeter and area of rectangles · Unit 15 Shapes, area and volume

1 · Teaching slidesuse ← → keys

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2 · Key words

perimeterThe distance all the way round a shape.

areaThe amount of surface a shape covers.

square centimetreThe area of a square 1 cm by 1 cm.

congruentSame shape and same size; corresponding sides and angles equal.

formulaA rule written with letters.

dimensionOne of the measurements of a shape.

3 · Summary of the sectionrevise from this

Perimeter is the distance round the edge. It is a length, measured in mm, cm, m or km.
Area is the surface covered. It is measured in square units, because it is a length times a length.
Rectangle: perimeter = 2(l + w) and area = l × w.
Square of side s: perimeter = 4s and area = s².
To work backwards from an area, divide: width = area ÷ length.
To work backwards from a perimeter, take off the two sides you know first, then halve what is left.
Two shapes are congruent when corresponding sides and angles are equal — same shape and same size.
Equal areas do not make shapes congruent: 6 × 4 and 12 × 2 both give 24 cm².
Doubling both sides multiplies the area by 4, not by 2.

PDFPrintable worksheet All 67 questions, space to work PDFWorked answers Full solutions, not just the answer

Video lessons1 videos

Area of a Rectangle

British corbettmaths

Length times width, and keeping perimeter and area apart.

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Perimeter and area of rectangles