This document discusses calculating the area of triangles. It provides the formulas for finding the area of a triangle using base (B) and height (H): A = 1/2 x B x H. Several examples are worked through, applying the formula to find the area when given values for B and H. The document also shows how to find the height or base when given the other variable and the area. It concludes with a couple multi-triangle area problems, using the triangle area formula to calculate total area.

1. The AREA OF THE TRIANGLE
Mrs.Neveen kamel
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2. Area of the triangle
Width
Length Base
Height
A =L x W=……Cm² A =½ A
A =½ x L x W
A =½ x B x H

3. B = 2 cm. H = 3 cm. A = ?3 cm²
B = 4 cm. H = 6 cm. A =12 cm²
B = 0.2 cm. H = 0.4 cm. A = 0.04 cm²
?
?

4. A
½ B H
B= 2A ÷ H H= 2A ÷ B
A = ½ x B x H
2A= B x H

5. Calculate the area of ABC in each of following :
B
A
C
A
B C
A
B DC3.6cm.
3.6cm.
12cm.
4cm.
3cm.
8cm.
A = ½ x B x H
= ½ x 3 x 4
= 6 cm².
A = ½ x B x H
= ½ x 12 x 8
= 48 cm².
A = ½ x B x H
= ½ x 3.6 x 3.6
= 6.48 cm².

6. If the area of a triangle is 12 cm².find :
[a] Its height , if its corresponding
base length is 6 cm.
H= 2A ÷ B
= 2 x 12 ÷ 6
= 4 cm².
[b] Its base length , if its
corresponding height length is 8 cm.
H = 2A ÷ B
= 2 x 12 ÷ 8
= 3 cm².

7. Calculate the area of the following figure :
D
A
C
3cm.
5 cm.
4cm.
B
E
A = ½ x 5 x 4
= 20 cm².
A = 3 x 5
= 15 cm².
A = A +A
=15+20
=35 cm².

8. In the following figure find the area of the
shaded part :
A
C
D B
E
10 cm.
6cm.
A1 = ½ x 10 x 6
=
A2 = ½ x 10 x 3
=
?
?
30 cm².
15cm².
A = A1-A2
= 30-15
=15 cm².