1. Areas of Parallelograms & Triangles
Tutorial 13b

2. Parallelograms
You can choose any side of a parallelogram to be a base.
An altitude is any segment perpendicular to the line containing the base drawn from the side opposite the base.
The height is the length of the altitude.
height
base

3. Area of a Parallelogram
The area of a parallelogram is the product of any base and the corresponding height.
A = bh h b

4. Area of a Parallelogram
The area of a parallelogram is the product of any base and the corresponding height.
A = bh
A = 5•3
A= 15 3 5

5. 2. 4 12 8 4
A = bh
A = 12•4
A = 48 units2
A = bh
A = 4•8
A = 32 units2

6. A = bh A = 8•4 A = 32 Find the value of x in each parallelogram below.3. 4. 8
A = bh
A = 8•4
A = 32
Use one set of base & height to find the area. After knowing the area, use the other base with the unknown height (x) and the area formula to solve for x.
Click here to continue

7. Find the value of x in each parallelogram below.3. 4. 5 8 x
A = bh
A = 8•4
A = 32
Use one set of base & height to find the area. After knowing the area, use the other base with the unknown height (x) and the area formula to solve for x.
32= bh
32= 5x
= x

8. Find the value of x in each parallelogram below.3. 4. 5 8 x
A = bh
A = 8•4
A = 32
Try #4 on your own, then click below to check your answers.
Check Answer
32= bh
32= 5x
= x

9. A = bh A = bh A = 8•4 A = 19•11 A = 32 A = 209 209= bh 209= 12x = x
Find the value of x in each parallelogram below. 3. 4. 5 8 x
A = bh
A = 8•4
A = 32
A = bh
A = 19•11
A = 209
209= bh
209= 12x
= x
32= bh
32= 5x
= x

10. Triangles You can choose any side of a triangle to be the base.
The corresponding height is the length of an altitude drawn to the line containing the base.
height
base

11. Area of a Triangle
The area of a triangle is half the product of any base and the corresponding height. h b

12. Example #1 A = 1/2 •20•6 A = 60 ft2 Find the area of this triangle

13. The End
Time to move on
to the assignment or
the next lesson