# Grade 6 2 02 Solve problems involving perimeter

Grade 6: 2. 02 Solve problems involving perimeter/ circumference and area of plane figures

Area is the amount of surface space that a flat object has. Area is reported in the amount of square units.

When you measure the amount of carpet to cover the floor of a room, you measure it in square units. Would the area of your bedroom or the area of your house be greater? You’re right! The area of your house is greater than the area of your bedroom.

Lets find the area of this surface if each square is equal to one foot. Count the number of squares. 1 2 Area = 15 square feet 3 4 5 6 7 8 9 10 11 12 13 15 14

Try this one! 1 2 3 4 5 6 7 8 9 Count the number of green squares to determine the area of this surface. What is the area? The area is equal to 9 square units.

Perimeter is the distance around the outside edge of a flat object. Perimeter is reported as a total number of linear units.

When you measure the amount of wallpaper border to go around a room, you measure it in lengths. Would the perimeter of your bedroom or the perimeter of your house be greater? You’re right! The perimeter of your house is greater than the perimeter of your bedroom.

Let’s find the perimeter of this surface if each square is equal to one foot. Count the number of sides. Perimeter = 24 feet

Try this one! Count the number of sides to determine the perimeter of this flat object. The perimeter is equal to 12.

Let’s do these problems together. Two neighbors build swimming pools. This is what the pools look like. Which family has the pool with the bigger swimming area? Family A Family B

The area of Family A’s pool is? 8 square units. The area of Family B’s pool is? 7 square units Therefore, Family A has the pool with the bigger swimming area. Family A Family B

Now look at those same two pools. Which family has more side panels of the pool to clean? The perimeter of Family A’s pool is 12 units long. The perimeter of Family B’s pool is 14 units long. Therefore, Family B has more side panels of the pool to clean. Family A Family B

Calculate the Circumference Using the Correct Formula

How to calculate the circumference C= Diameter = 12 cm Πd Always, write the formula (rule) C = 3. 14 X 12 C = 37. 68 The symbol is the Greek letter pi. It stands for a number that can never be found exactly. It is approximately 3. 14

How to calculate the diameter from the circumference Always, write the If the circumference is 40 cm. evaluate the DIAMETER Diameter = ? cm formula (rule) d=C÷Π d = C ÷ 3. 14 d = 40 ÷ 3. 14 d = 12. 73

1 2 3 4 5 6 7 8 9 10 Diameter 24 14 Radius Circumference 17 30 22 120 78 88 Remember d=2 Xr r=d÷ 2 120 340

1 2 3 4 5 6 7 8 9 10 Diameter 24 14 34 60 22 120 156 176 38. 22 108. 28 Radius 12 7 17 30 11 60 78 88 19. 11 54. 14 Circumference 75. 36 43. 96 106. 76 188. 4 69. 08 376. 8 489. 84 552. 64 120 340

The Circle 1. Calculate the area of a circle RADIUS The distance from the centre to the edge DIAMETER The distance from one side to the other passing through the centre Π = 3. 14 (approximately) D = 2 x R and R = D ÷ 2

How to calculate the area Always, write the formula (rule) A = πr 2 Radius = 6 A = 3. 14 x r A = 3. 14 x 6 A = 113. 04 cm 2

Calculate the areas of the following circles 1 Radius = 10 cm 5 Diameter = 24 cm 2 Radius = 15 cm 6 Diameter = 21 cm 3 Radius = 13. 5 cm 7 Diameter = 3. 8 cm 4 Radius = 8. 75 cm 8 Diameter = 12. 5 cm

Calculate the areas of the following circles 1 314 cm 2 5 452. 16 cm 2 2 706. 5 cm 2 6 346. 19 cm 2 (2 dp) 3 572. 265 cm 2 7 11. 34 cm 2 (2 dp) 4 240. 41 cm 2 (2 dp) 8 122. 66 cm 2 (2 dp)

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