Perimeter Of Regular Plane Shapes

The perimeter of a plane shape is the length of its outside boundary or the distance around its edges.

Irregular shape

An irregular shape does not have a definite shape. To determine the perimeter of such shape, string or thread can be used to measure it. Place the string around the edge, then straighten it out and measure it with a ruler from the mark part.

Regular Shape

A regular shape has a well-defined edge which may be straight lines or smooth curves. Examples are regular polygon and circles

The unit of measurement

Perimeter is measured in length units. These are kilometres (km), metres (m), centimetres (cm) and millimetres (mm).

General Evaluation/Revision Questions

1. A regular polygon has all its sides …………… and all its angles …………..
2. The distance around the circle is ………………………..
3. What is the perimeter of a rhombus if the length of one side is 8cm?
4. A circle of diameter 21cm has a perimeter of 66cm. If the circle is halved. Determine the perimeter of the half.

Reading Assignment

Essential Mathematics for J.S.S 1 by A. J. S Oluwasanmi, page 198-209.

Weekend Assignment

1. What is the perimeter of a rectangle that measures 11cm by 3cm. (a) 39cm  (b) 28cm   (c) 36cm   (d)  26cm
2. The diameter of a circle is 13.8cm long. Find the length of its radius (a) 27.6cm  

(b) 7.6cm (c) 6.9cm   (d) 6.4cm

• Two sides of an isosceles triangle are 3cm and 10cm. What must be the length of the third side?  (a) 10cm  (b) 6cm   (c)  4cm  (d) 8cm
• If the width of a rectangle is  the equal to the length of a square and  the rectangle measures 6cm by 4cm. What is the difference perimeter of the square?  (a) 26cm

(b) 16cm  (c) 24cm   (d) 36cm

• What is the difference in the perimeter of the rectangle and the square in question 4 above? (a)  4cm  (b)  6cm  (c)  8cm  (d)  2cm

Theory

1. The diameter of a car wheel is 28cm, find its circumference. How far does the car move in metres when the wheel makes 150 turns? ( Take )
2. (a) The longer side of a rectangle is 25cm and its perimeter is 80cm. Find the length of the shorter side. Determine its area

(b) The area of a parallelogram is 8.5m² and its base is 500cm. Find its height.