Area and perimeter of triangles
Topic Notes
In this lesson, we will learn:
- The basic properties of the shape of the triangle
- How to understand and calculate the perimeter of a triangle
- How to understand and calculate the area of a triangle
Notes:
- A triangle is a 2D shape with 3 straight sides and 3 angles that add up to 180°
- There are different types triangles (classified by side lengths or angle size), but it does not change the formulas for area and perimeter.
- The perimeter is the exact distance around the shape.
- Perimeter is a 1D (one-dimensional) quantity
- It uses units such as meters (m, cm, mm, km), miles (mi), yards (yd), or inches and feet (in and ft)
- For triangles, the formula is written as:
- Ptriangle = side1 + side2 + side3
- This formula does not change for different types of triangles
![2D Shapes: Area and Perimeter of Rectangles](
https://dmn92m25mtw4z.cloudfront.net/img_set/math5-15-5-x-1/v1/math5-15-5-x-1-763w.png)
- The area is the space that is covered by the shape.
- Area is a 2D (two-dimensional) quantity
- It uses squared units such as square meters (m2, cm2, mm2, km2), square miles (mi2), square yards (yd2), or square inches and feet (in2 and ft2)
- For triangles, the formula is written as:
- Areatriangle =
- Where is base, and is height
- This formula does not change for different types of triangles, but you do need to keep in mind how to find the triangle’s height
- The triangle’s base is any of the three straight sides
- The triangle’s height is found by placing the chosen base as the flat bottom, and then drawing a perpendicular line from that until the highest point (vertex); it can also be called the triangle’s altitude
![2D Shapes: Area and Perimeter of Rectangles](
https://dmn92m25mtw4z.cloudfront.net/img_set/math5-15-5-x-2/v1/math5-15-5-x-2-711w.png)