Properties of Triangles
Name a triangle from the ticks and the right-angle square on it, then draw one accurately from the lengths given.
Your child names triangles by their angles (right-angled, acute-angled, obtuse-angled) and by their sides (equilateral, isosceles), reading the ticks and right-angle squares on a figure as facts. Your child then finds unknown angles from the 180° angle sum, including the equal base angles of an isosceles triangle, and draws triangles accurately on a square grid and with a ruler and protractor. Read the study guide →
About this chapter
Primary 5 properties of triangles questions name a triangle from the ticks and angle marks on it, use the properties of isosceles, equilateral and right-angled triangles, and use the angle sum of a triangle. The chapter also draws triangles from the lengths and angles given.
Practise by question type: p5 drawing triangles questions, p5 types of triangles questions and p5 angles in a triangle questions.
The order to learn them
The building blocks
11.1
What do the marks say about the triangle?
11.2
Drawing the finished triangle
11.3
The number tells you where a question type sits in this chapter, not what your child needs to learn first. A child who has already met a type in school can practise it without working through the ones above it.
How the end-of-year papers set these questions
Modelled against the Primary 5 end-of-year papers
We write the questions ourselves. This chapter is modelled on the types of question set in the 2025 Primary 5 end-of-year papers.
Triangle questions appear in Paper 1 and Paper 2
A short question may ask for one unknown angle. Longer questions combine an isosceles or equilateral triangle with a straight line or another shape. Some questions ask for a triangle to be drawn on a grid or with a protractor.
The marks on the figure are part of the question
Equal-side ticks, equal-angle arcs and a right-angle square state facts that may not be written in the stem. Practice questions are not labelled by type, so children must read those marks before choosing a method.
Everything here is modelled against top school papers. Those papers are never reproduced, and every question on this site is original.
How to set out the working clearly
These examples show Mathweave's clear, consistent layout for each method. The layout is informed by the answer keys we reviewed.
- Read every mark before calculating Equal-side ticks show which sides are equal. The angles opposite those sides are equal. A right-angle square marks a 90° angle.
- Subtract before dividing by 2 For an isosceles triangle, subtract the third angle from 180° and divide the remainder by 2 on the same line.
- Write the reason beside each angle equation Name the angle, show the full calculation and put the property in brackets on the line where it is used.
- Number the construction steps and label the result Draw the given side first, measure the given angle or grid distance, then join the final vertex. Label every given length, angle and equal side on the completed triangle.
Questions parents ask
Is this on the Primary 5 syllabus?
Yes. The chapter follows the Triangle outcomes in the latest MOE Primary Mathematics syllabus.
Which practice is available now?
Original practice is available for triangle properties and angles in a triangle. Practice for drawing a triangle is being built.
Why does one lesson also appear in Primary 6?
Angles in a triangle are used at both levels. The question type has one lesson page with the level line Primary 5 and Primary 6.
Are the questions from past papers?
We write the questions ourselves rather than copy them from papers. Each chapter is modelled on the types of question that top school papers set. A question may look like one your child has met before because it is the same type.
What does the practice add over the films?
Practice uses different numbers for each question type, shows the working after every attempt and records which types your child can complete independently.
Primary 5 triangle properties questions by question type
Primary 5 Properties of Triangles Study Guide
Sort five kinds of triangle by their marks, watch three corners fill a straight line, then turn a grid staircase and build a triangle with a protractor. Worked examples and a five-question check follow.
Start hereFive kindsAngle sumOn a gridProtractorOpen the study guide →