Perimeter Area 1 st Year Maths Examples Metric

Perimeter & Area 1 st Year Maths

Examples Metric System Centimetres (cm) / Millimetres (mm) Imperial System Inches / 1/8 inches

Millimetres/Centimetres/Metres How many Millimetres in a centimetre? 1 cm = 10 mm

Millimetres/Centimetres/Metres How many centimetres in a metre? 1 m = 100 cm

Questions: Write the following as centimetres: (i) (iii) (iv) (vi) 40 mm 65 mm 15 cm 7 mm 76 mm 1. 2 metres 3. 5 metres Answers: (i) 40 mm = 4 cm (ii) 65 mm = 6. 5 cm (iii)15 cm 7 mm = 15. 7 cm (iv)76 mm = 7. 6 cm (v) 1. 2 m = 120 cm (vi)3. 5 m = 350 cm

First we need to find he length of each side by counting the squares. 8 cm 6 cm The distance around the outside of a shape is called the perimeter. 8 cm The perimeter of the shape is 8 + 6 + 8 + 6 = 28 cm.

18 cm What is the perimeter of each of these shapes? 22 cm 26 cm

Now find the perimeter of these shapes. They are not drawn to scale. 5 cm 3 cm 4 cm 3 cm 7 cm 3 cm Perimeter = 18 cm 4 cm 3 cm 3 cm 4 cm 3 cm Perimeter = 22 cm Perimeter = 28 cm

Area of Rectangle/Square Area of Rectangle = Length x Width

Finding the length of the square Q: Find the length of the square. AREA = 64 cm 2 1. What do we know about the length of each side of the square? 2. What number would we have to multiply by itself to give us an area of 64 cm 2? Answer = 8 cm x 8 cm = 64 cm 2

Finding the length of a rectangle Q: Find the length of this rectangle 8 cm Area = 72 cm 2 1. What information do we know about the rectangle? 2. Because Area = L x W. We must decide what number we multiply 8 cm by to get an answer of 72 cm 2. 3. Answer = 9 cm

Finding the area of irregular shapes Q: How can we find the area of this shape? 4 cm 7 cm 9 cm 6 cm 2 cm 10 cm

Method Split the shape into two rectangles. We know how to find the area of a rectangle. 4 cm 7 cm 9 cm B 6 cm A 10 cm 2 cm

Find the Area Now find the area of each rectangle and add them together! Easy! A 10 cm 2 cm Area of Rectangle A = L x W Area = 10 cm x 2 cm Area = 20 cm 2

4 cm Area Rectangle B = L x W 7 cm B Area = 4 cm x 7 cm Area = 28 cm 2

Find the total area Total Area = Area Rectangle A + Area of Rectangle B 4 cm 7 cm 9 cm 6 cm Total Area = 20 cm 2 + 28 cm 2 Total Area = 48 cm 2 2 cm 10 cm

Questions to complete: Page 154/155/156 Q 4 Q 7 Q 8 Q 10 Homework: Page 154/155 Q 3, Q 6, Q 9

Area of Triangle = ½ Base x Perpendicular Height 8 cm 7 cm 10 cm The perpendicular height means it is at a right angle to the base.

Find the Area 8 cm 7 cm 10 cm Area of Triangle = ½ Base x Perpendicular Height = ½ x 10 cm x 7 cm = 5 cm x 7 cm = 35 cm 2

Find the missing value Find the value of x in the triangle Area = 54 cm 2 x 12 cm 1. Examine the information we know about the triangle. What do we know? 2. Remember how we find the area of a triangle: Area = ½ B x H 3. Decide what number we need to multiply by half of our base of 12 cm to get an answer of 54 cm 2 4. What will our answer be? Answer : ½ x 12 cm x ? = 54 cm 2 6 cm x ? = 54 cm 6 cm x 9 cm = 54 cm So x = 9 cm

Questions: Page 156/157 Q 13 Q 14, Q 15, Q 16 (iii) Homework Page 156/157/158 Q 12 Q 16 (i) (ii) Q 21