Geometry: Angles and Triangles


Videos, worksheets, solutions and activities to help students learn about angles in Singapore Math.

Related Topics:
More Geometry Lessons
Singapore Math




Share this page to Google Classroom

In this lesson, we will learn

  • what is an angle?
  • what are angles on a straight line, angles at a point and vertically opposite angles?
  • what is an isosceles triangle, an equilateral triangle and a right-angled triangle?
  • what is the sum of angles in a triangle?
  • how to draw different types of triangle?
  • how to find unknown angles in a four-sided figure?
  • how to draw a parallelogram, rhombus and trapezium?

Geometry - Introduction to angles
An explanation of what an angle is.

Geometry - Finding unknown angles
An explanation of

  1. Sum of angles on a straight line
  2. Sum of angles at a point
  3. Vertically opposite angles.

Geometry - Different types of triangles
What is an isosceles triangle, an equilateral triangle and a right-angled triangle?

Geometry - Angle sum of a triangle
Why is the sum of angles of a triangle = 180 degrees?




Geometry - Drawing triangles using instruments - Example 1
Learn how to draw an equilateral triangle using geometrical instruments.

Geometry - Drawing triangles using instruments - Example 2
Learn how to draw an isosceles triangle using geometrical instruments.

Geometry - Drawing triangles using instruments - Example 3
Learn how to draw a triangle using geometrical instruments.

Geometry - Finding unknown angles in four-sided figures - Example 1
How do you find unknown angles in a four-sided figure?



Geometry - Finding unknown angles in four-sided figures - Example 2
How do you find unknown angles in a four-sided figure?

Geometry - Finding unknown angles in four-sided figures - Example 3
How do you find unknown angles in a four-sided figure?

Geometry - How to draw a parallelogram using instruments?

Geometry - How to draw a rhombus with instruments?

Geometry - How to draw trapezium with instruments?

Try out our new and fun Fraction Concoction Game.

Add and subtract fractions to make exciting fraction concoctions following a recipe. There are four levels of difficulty: Easy, medium, hard and insane. Practice the basics of fraction addition and subtraction or challenge yourself with the insane level.

Fraction Concoction Game



We welcome your feedback, comments and questions about this site or page. Please submit your feedback or enquiries via our Feedback page.