CDEF is a rectangle which has a breadth of 12 cm. It is divided into 4 triangles. Triangle G is
112 of the area of the rectangle and
13 the area of Triangle J. Triangle H has an area of 46 cm
2.
- Find the area of the rectangle.
- Find the perimeter of the rectangle.
G |
H |
J |
Rectangle |
1 |
|
|
12 |
1 |
|
3 |
|
1 u |
2 u |
3 u |
12 u |
(a)
Area of Triangle H
= Half of Rectangle CDEF - Triangle J - Triangle G
= (12 u ÷ 2) - 1 u - 3 u
= 2 u
2 u = 46
1 u = 46 ÷ 2 = 23
Area of the rectangle
= 12 u
= 12 x 23
= 276 cm
2 (b)
Length of the rectangle
= 276 ÷ 12
= 23 cm
Perimeter of the rectangle
= 23 x 2 + 12 x 2
= 70 cm
Answer(s): (a) 276 cm
2; (b) 70 cm