STUV is a rectangle which has a breadth of 12 cm. It is divided into 4 triangles. Triangle W is
112 of the area of the rectangle and
13 the area of Triangle Y. Triangle X has an area of 42 cm
2.
- Find the area of the rectangle.
- Find the perimeter of the rectangle.
W |
X |
Y |
Rectangle |
1 |
|
|
12 |
1 |
|
3 |
|
1 u |
2 u |
3 u |
12 u |
(a)
Area of Triangle X
= Half of Rectangle STUV - Triangle Y - Triangle W
= (12 u ÷ 2) - 1 u - 3 u
= 2 u
2 u = 42
1 u = 42 ÷ 2 = 21
Area of the rectangle
= 12 u
= 12 x 21
= 252 cm
2 (b)
Length of the rectangle
= 252 ÷ 12
= 21 cm
Perimeter of the rectangle
= 21 x 2 + 12 x 2
= 66 cm
Answer(s): (a) 252 cm
2; (b) 66 cm