CDEF is a rectangle which has a breadth of 13 cm. It is divided into 4 triangles. Triangle G is
113 of the area of the rectangle and
13 the area of Triangle J. Triangle H has an area of 72.5 cm
2.
- Find the area of the rectangle.
- Find the perimeter of the rectangle.
G |
H |
J |
Rectangle |
1 |
|
|
13 |
1 |
|
3 |
|
1 u |
2.5 u |
3 u |
13 u |
(a)
Area of Triangle H
= Half of Rectangle CDEF - Triangle J - Triangle G
= (13 u ÷ 2) - 1 u - 3 u
= 2.5 u
2.5 u = 72.5
1 u = 72.5 ÷ 2.5 = 29
Area of the rectangle
= 13 u
= 13 x 29
= 377 cm
2 (b)
Length of the rectangle
= 377 ÷ 13
= 29 cm
Perimeter of the rectangle
= 29 x 2 + 13 x 2
= 84 cm
Answer(s): (a) 377 cm
2; (b) 84 cm