the distance around an enclosed shape is called the perimeter. the amount of space enclosed inside a...
TRANSCRIPT
PERIMETER AND AREA
The distance around an enclosed shape is called the perimeter.
The amount of space enclosed inside a shape is called the area.
Area of a rectangle
base
height
Area of rectangle = base × height
Area of a triangle
base
Area of triangle = ½ × base × height
height
Area of a parallelogram
A parallelogram can be made into a rectangle.
base
height
Area of parallelogram = base × height
Area of a trapezium
Two identical trapeziums can be made into a parallelogram.
a
h
Area of parallelogram = ½ (a + b) h
b
b
a
10
8
Examples1 Find a the perimeter b the area of the shape. All lengths are in cm.
24 42
66 cm2
Area (8 3) (7 6)
7
6
10
8
7
6
2
3 Perimeter 3 2 7 6 10 8
36 cm
a
b
10 cm
3 cmExamples2 Find the area of the parallelogram.
10 3
30 cm2
Area base height
6 cm
4 cmExamples3 Find the area of the triangle.
1
26 4
12 cm2
Area
1
2base height
Examples4 Find the area of the trapezium. All lengths are in cm.
1
2(5 2) 3
10.5 cm2
Area
1
2(a b)h
5
3
2
1
27 3
1
221
Examples5 The area of the trapezium is 24 cm2. Find the value of x.
24
1
2(2x 3 x) 4
x 3
Area
1
2(a b)h
2x+3
4 cm
x
24
1
2(3x 3) 4
24 2(3x 3)
24 6x 6
18 6x