CDEF is a rectangle which has a breadth of 8 cm. It is divided into 4 triangles. Triangle G is
111 of the area of the rectangle and
13 the area of Triangle J. Triangle H has an area of 28.5 cm
2.
- Find the area of the rectangle.
- Find the perimeter of the rectangle.
G |
H |
J |
Rectangle |
1 |
|
|
11 |
1 |
|
3 |
|
1 u |
1.5 u |
3 u |
11 u |
(a)
Area of Triangle H
= Half of Rectangle CDEF - Triangle J - Triangle G
= (11 u ÷ 2) - 1 u - 3 u
= 1.5 u
1.5 u = 28.5
1 u = 28.5 ÷ 1.5 = 19
Area of the rectangle
= 11 u
= 11 x 19
= 209 cm
2 (b)
Length of the rectangle
= 209 ÷ 8
= 26.125 cm
Perimeter of the rectangle
= 26.125 x 2 + 8 x 2
= 68.25 cm
Answer(s): (a) 209 cm
2; (b) 68.25 cm