Year 7 · Maths · Lines and angles · Lesson 4
Types of triangle and constructing triangles
Name types of triangle, construct triangles from two sides and the included angle, and decide whether a triangle can be drawn.
23-minute video lesson
Teaching, worked examples and 20 practice questions solved step by step.
Watch free for a monthWhat your child will learn
- Name types of triangle
- Use properties of isosceles and equilateral triangles
- Construct a triangle accurately
- Measure lengths and angles
- Decide if a triangle is possible
The method
- Sketch first, with the measurements.
- Draw the base accurately with a ruler.
- Use a protractor for the angles.
- Label everything; measure to the nearest mm.
Key words: equilateral, isosceles, scalene, construct, protractor.
Worked examples
The first three practice questions from the lesson, with every step.
Question 1
What type of triangle has angles 60°, 60°, 60°?
- Step 1: All angles 60°: equilateral
Answer: Equilateral
Question 2
What type of triangle has angles 70°, 70°, 40°?
- Step 1: Two equal angles: isosceles
Answer: Isosceles
Question 3
What type of triangle has angles 30°, 60°, 90°?
- Step 1: One angle is 90°: right-angled. No equal angles: scalene
Answer: Right-angled (and scalene)