# Constructing triangles

## Lesson details

### Key learning points

1. In this lesson, we will learn how to construct triangles using a pair of compasses and ruler given the length of the sides. We will need a pair of compasses, pencil and ruler for this lesson.

### Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

## Video

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## Worksheet

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## Starter quiz

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### 6 Questions

Q1.
Label this part of the circle
Diameter
Tangent
Q2.
Label this part of the circle
Arc
Circumference
Q3.
Label this part of the circle
Arc
Circumference
Diameter
Q4.
What is the circumference of a circle?
The circumference is also the radius of a circle
The circumference is the area of the circle
Correct answer: The circumference is the distance around a circle
Q5.
Complete the sentence. The diameter of a circle is...
Half the radius of the circle
Others
The length of the circle
The same as the radius of a circle
Q6.
The radius of my circle is 8.5cm. What is the diameter of the circle?
16cm
4.25cm
8.5cm

## Exit quiz

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### 5 Questions

Q1.
If you know the length of the sides of a triangle, you can _______ it using a pair of ______.
construct, protractor
draw, compass
make,ruler
Q2.
This circle is drawn on a centimetre square grid. State the radius and diameter.
Radius = 2cm, Diameter = 2cm
Radius = 4cm, Diameter = 2cm
Q3.
This circle is drawn on a centimetre square grid. State the radius and diameter.
Correct answer: R = 1cm, D = 2cm
R = 1cm; D = 1cm
R = 2cm; D = 1cm
Q4.
This circle is drawn on a centimetre square grid. State the radius and diameter.
Others
R = 4cm, D = 4cm
Correct answer: R = 4cm, D = 8cm.
R= 8cm, D = 4cm
Q5.
Two students were asked to construct a triangle with side lengths 3 cm , 2 cm and 4 cm. Are they both correct?
No, they are not both correct. Only B is correct because she mentioned the shortest angle first then measured the rest.
No, they are not both correct. Only student A is correct because the base is 3cm.
Correct answer: Yes, they are both correct because both of the triangles are identical (congruent) but they are orientated differently.