Area and perimeter of triangles

Area and perimeter of triangles

Lessons

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

  • 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 = b×h2\large \frac{b \, \times \, h} {2}
        • Where bb is base, and hh 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
  • Introduction
    Introduction to Area and Perimeter of Triangles:
    a)
    What are the basic properties of a triangle?

    b)
    How do you calculate the perimeter of a triangle?

    c)
    How do you calculate the area of a triangle?


  • 1.
    Perimeter of Triangles
    Calculate the perimeter of each triangle.
    a)

    2D Shapes: Area and Perimeter of Rectangles

    b)

    2D Shapes: Area and Perimeter of Rectangles

    c)

    2D Shapes: Area and Perimeter of Rectangles


  • 2.
    Area of Triangles
    Calculate the area of each triangle.
    a)

    2D Shapes: Area and Perimeter of Rectangles

    b)

    2D Shapes: Area and Perimeter of Rectangles

    c)

    2D Shapes: Area and Perimeter of Rectangles


  • 3.
    Perimeter and Area of Compound Triangle Shapes
    Calculate the perimeter and area of each compound shape. Break down the complex shapes into components (triangles and rectangles) first!
    a)

    2D Shapes: Area and Perimeter of Rectangles

    b)

    2D Shapes: Area and Perimeter of Rectangles

    c)

    2D Shapes: Area and Perimeter of Rectangles


  • 4.
    Triangles Word Problem
    The side of a skateboard ramp is a right triangle. What is the perimeter and area of the side of a skateboard ramp that has the following measurements: base=20m, height=15m, slope=25m

    2D Shapes: Area and Perimeter of Rectangles