Succeed with maths – Part 2
Succeed with maths – Part 2

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

Succeed with maths – Part 2

2.3 Perimeters of mixed shapes

Suppose the shape that you wanted to determine the perimeter of is as shown in Figure 15.

Described image
Figure 15 A shape formed of a rectangle and two semicircles

Start by noticing that the shape is formed of one rectangle and two semicircles. The distance around the two semicircles combined is the same as around a circle with a diameter of 1.6 m. So, calculating the circumference of a circle with this diameter will give us part of the answer. To find the total distance, or perimeter, you then just need to add in the lengths of the longest edges of the rectangle. This gives us the following calculation:

multiline equation line 1 Circumference of circle equals pi multiplication diameter line 2 equation left hand side equals right hand side pi multiplication 1.6 m line 3 equals 5.03 m left parenthesis to two decimal places right parenthesis

multiline equation line 1 Total perimeter equals 5.03 m prefix plus of two multiplication two m line 2 equals 9.03 m left parenthesis to two decimal places right parenthesis

So, if you are faced with a complex shape, look for ways to split these up to help you calculate the perimeter.

Another property of a shape that can be useful to know is the area, or space that it occupies. This is slightly more complicated than the perimeter, but for regular shapes there are a set of formulas to help with this, as you will see in the next section.

Skip Your course resources
SWMB_2

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371