GHJK is a rectangle which has a breadth of 5 cm. It is divided into 4 triangles. Triangle L is
111 of the area of the rectangle and
13 the area of Triangle N. Triangle M has an area of 10.5 cm
2.
- Find the area of the rectangle.
- Find the perimeter of the rectangle.
L |
M |
N |
Rectangle |
1 |
|
|
11 |
1 |
|
3 |
|
1 u |
1.5 u |
3 u |
11 u |
(a)
Area of Triangle M
= Half of Rectangle GHJK - Triangle N - Triangle L
= (11 u ÷ 2) - 1 u - 3 u
= 1.5 u
1.5 u = 10.5
1 u = 10.5 ÷ 1.5 = 7
Area of the rectangle
= 11 u
= 11 x 7
= 77 cm
2 (b)
Length of the rectangle
= 77 ÷ 5
= 15.4 cm
Perimeter of the rectangle
= 15.4 x 2 + 5 x 2
= 40.8 cm
Answer(s): (a) 77 cm
2; (b) 40.8 cm