Perimeter of a Semi-Circle

Welcome to our Perimeter of a Semi-Circle page.

Here you will find a range of free printable perimeter sheets and support, which will help your child to learn to calculate the perimeter of a range of semi-circles.

Perimeter of a Semi-Circle

On this webpage you will find our range of worksheets to help your child learn to work out the perimeter of a range of semi-circles.

These sheets are graded from easiest to hardest, and each sheet comes complete with answers.

Using these sheets will help your child to:

  • understand what perimeter is;
  • know how to find the perimeter of a semi-circle;
  • solve word problems involving perimeter of semi-circles;

What is Perimeter?

  • Perimeter is the distance around the outside of a shape.
  • It can be measured in cm, inches, feet, yards, km, miles, etc.

A good way of thinking about the perimeter of a shape in front of you is to imagine that you are very small and standing on one of the corners of the shape. Imagine walking along the edge of the shape until you get back to where you started. The distance you have walked will be the perimeter.

perimeter image 2

For more help with perimeter please use: this link.

How to find the Perimeter of a Semi-Circle

perimeter of a semi circle image

The perimeter of the semi-circle is the same as half of the perimeter of a circle the same size, with the diameter added on.

To find the perimeter of a semi-circle, follow these simple steps:

  • find the diameter of the semi-circle (the distance of the straight line along the bottom of the semi-circle)
  • find the radius of the circle by halving the diameter.
  • multiple the radius by pi (or π) to find the perimeter of the curved part
  • add on the diameter of the circle.

The formula for the circumference of a circle is C = π r + d,
where C is the circumference, r is the radius and d is the diameter.

Re-writing the formula in terms of the radius: C = π r + 2r.

Re-writing the forumla in terms of the diameter: C = ½ π d + d.

Pi is a special mathematical number which is used to help calculate areas and perimeters of circles.

Pi always has the same value which is 3.141592...

Perimeter of a Semi-Circle Example 1

Find the perimeter of the semi-circle below to 1 decimal place.

semi circle perimeter example 1

To find the perimter of a circle, we need to multiply the radius by pi (π), then add on the diameter.

The radius of the semi-circle is 6 ÷ 2 = 3 cm

So the perimeter of this semi-circle is π r + d = π x 3 + 6 cm

If we take π = 3.14, the perimeter is 3.14 x 3 + 6 = 15.4 cm (to 1 decimal place).

Perimeter of a Semi-Circle Example 2

Find the perimeter of the semi-circle below to the nearest inch.

semi circle perimeter example 2

To find the perimter of a circle, we need to multiply the radius by pi (π), then add on the diameter.

The radius of the semi-circle is 11 ÷ 2 = 5.5 inches

So the perimeter of this semi-circle is π r + d = π x 5.5 + 11 inches.

If we calculate this to the nearest cm, the perimeter is 3.14 x 5.5 + 11 = 28 inches (to the nearest inch).

Perimeter of a Circle Example 3

Find the perimeter of the semi-circle below and give your answer to 1 decimal place.

semi circle perimeter example 3

To find the perimter of a circle, we need to multiply the radius by pi (π), then add on the diameter.

The radius of the semi-circle is 5 ft, so the diameter is double this which is 10 ft.

So the perimeter of this semi-circle is π r + d = π x 5 + 10 ft

If we calculate this to 2 decimal places, the perimeter is 3.14 x 5 + 10 = 25.7 ft.

Perimeter of a Semi-Circle Worksheet Area

Circumference of a Semi-Circle Worksheets

Perimeter of a Semi-Circle Word Problems

Sheets 1A and 1B contains straightforward perimeter problems involving semi-circles.

Sheets 2A and 2B contain harder word problems that require more thinking to solve!

More Recommended Math Worksheets

Take a look at some more of our worksheets similar to these.

More Circle Worksheets and Support

Take a look at our other circle worksheets.

More Perimeter Support and Resources

We have more perimeter resources and worksheets.

Check out the pages below!

Area Worksheets

Here is our selection of free printable area worksheets for 3rd and up.

Using these sheets will help your child to:

  • work out the areas of a range of rectangles;
  • find the area of rectilinear shapes;
  • find the areas of a right triangle and different quadrilaterals.
 

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Follow these 3 easy steps to get your worksheets printed out perfectly!

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