The document discusses formulas for calculating the areas of triangles and trapezoids. For triangles, the area formula is 1/2 base × height. For trapezoids, the area formula is 1/2 × (sum of the two bases) × height. Several examples are provided to demonstrate calculating areas using these formulas.

1. Area of Triangles and Trapezoids

2. Area of a Triangle
There are several different kinds of triangles.
1
A = bh
2
The formula for area of a triangle is
because a triangle is half of a parallelogram.

3. Try it!
1
A= bh
8 cm 2
A= 1 6
12 cm (12)(8)
1
2
A = 48 cm2

4. Try it!
1
A= 2
bh
5 cm 7 cm
9 cm 1 45
A= 2
(9)(5)
A = 22.5cm 2

5. You can see that the height is the distance between
the bases. The base is the sum of the two parallel
sides. So, the trapezoid is ½ of the created
parallelogram.
b2
b1 b2
•So the formula is ½(b1 + b2 )h

6. You try it!
Find the area of this trapezoid.
1
A = (b1 + b2 )h
10 in 2
7
3 in 1 14
A= (4 + 10)3
1 2
4 in
2
A = 21 in

7. 1
A= (b1 + b2 )h
6 in 2 in
2
8 in 4
1 8
A= (6 + 2)8
1 2
2
A = 32 cm