Areas of Parallelograms & Triangles

Tutorial 13b

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.

base

height

Area of a Parallelogram

• The area of a parallelogram is the product of any base and the corresponding height.

A = bh

b

h

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= 155

3

8

4

124

A = bhA = 4•8A = 32 units2

A = bhA = 12•4A = 48 units2

2.

8

3. 4.

Find the value of x in each parallelogram below.

A = bhA = 8•4A = 32

Click here to continue

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= bh32= 5x

= x

8

5

32

3. 4.

Find the value of x in each parallelogram below.

A = bhA = 8•4A = 32

5

x

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= bh32= 5x

= x

8

5

32

3. 4.

Find the value of x in each parallelogram below.

A = bhA = 8•4A = 32

5

x

Check Answer

Try #4 on your own, then click below to check your answers.

32= bh32= 5x

= x

8

5

32

3. 4.

Find the value of x in each parallelogram below.

A = bhA = 8•4A = 32

5

x

A = bh A = 19•11 A = 209209= bh209= 12x

= x12

209

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.

base

height

Area of a Triangle

• The area of a triangle is half the product of any base and the corresponding height.

bhA2

1

b

h

Example #1

• Find the area of this triangle

bhA2

1

20 ft

6 ftA = 1/2 •20•6A = 60 ft2