🔺 Welcome to the World of Triangles!
Below, you'll find interactive triangle diagrams you can move and explore.
A triangle is a flat shape (polygon) with 3 straight sides and 3 corners (vertices). It's one of the most important shapes in math and you can find triangles everywhere around you!
Try moving the corners (vertices) of this triangle to see how its shape changes:
Parts of a Triangle
- Sides: The 3 straight line segments that make up the triangle
- Vertices: The 3 corners where the sides meet (one vertex, two or more vertices)
- Angles: The space between two sides at each corner, measured in degrees
Here's a triangle with all its parts labeled:
Equilateral Triangle
All 3 sides are the same length
All 3 angles are also equal, each is \(60°\)
🎯 How to Measure Triangle Sides
- Place a ruler along one side of the triangle so that 0 is at one end
- Read the number at the other end of the side
- Write down that measurement
- Repeat for all three sides
In this diagram, the side lengths change when you move the corners—just like measuring with a ruler:
📏 What is Perimeter?
Perimeter is the distance around the outside of a shape.
To find the perimeter of a triangle, we add all three side lengths!
The Perimeter Formula:
If the sides of a triangle are \(a\), \(b\), and \(c\), then the perimeter is:
$$P = a + b + c$$
or simply: Add all the sides together!
Try this interactive perimeter calculator: