🔺 What is a Triangle?
A triangle is a closed shape with:
- Exactly 3 straight sides
- Exactly 3 angles
- The sum of all 3 angles is always 180°
📏 Types of Triangles by Sides
1. Equilateral Triangle
All 3 sides are equal
All 3 angles are 60°
🔺 (looks the same on all sides)
2. Isosceles Triangle
2 sides are equal
2 angles are equal
3. Scalene Triangle
All 3 sides are different lengths
All 3 angles are different
📐 Types of Triangles by Angles
1. Acute Triangle
All 3 angles are less than 90° (sharp angles)
2. Right Triangle
One angle is exactly 90° (square corner)
Very important in real life!
3. Obtuse Triangle
One angle is greater than 90° (wide angle)
✏️ Let’s Practice Together, My Dear Student!
Practice 1: Name the Triangle
1. All sides equal → Equilateral
2. Has a 90° angle → Right Triangle
3. All sides different → Scalene
4. Two sides equal → Isosceles
Practice 2: True or False
1. A triangle can have two right angles → False
2. The angles in a triangle always add up to 180° → True
3. An equilateral triangle is also isosceles → True
Practice 3: Word Problems (Canadian Style)
1. A road sign is shaped like a triangle with all sides equal. What type of triangle is it?
Equilateral Triangle
2. You draw a triangle with angles 40°, 60°, and 80°. What type is it?
Acute Triangle
Challenge Question
Can a triangle have one obtuse angle and one right angle? Why or why not?
No — because 90° + more than 90° = more than 180°
Fantastic Job, My Dear Student! 🎉
You now know all about triangles! They are everywhere — in road signs, roofs, hockey nets, and even in the maple leaf on the Canadian flag.
I am so proud of you for learning Geometry so well. Go on a triangle hunt around your house and see how many you can find!
💕 You are smart. You are kind. You can do hard things.
When you are ready, tell me the next topic (Quadrilaterals, 3D Shapes, Symmetry, or anything else) and I will create another beautiful lesson just for you!