Canada Grade 8 Math Area and perimeter of various shapes

What is the area of a rectangle with a length of 8 metres and a width of 5 metres?

• 13 square metres

• 40 square metres

• 30 square metres

• 20 square metres

Answer explanation

The area of a rectangle is calculated by multiplying the length by the width. Here, 8 metres (length) x 5 metres (width) = 40 square metres. Therefore, the correct answer is 40 square metres.

A triangle has a base of 10 cm and a height of 6 cm. What is its area?

• 30 square centimetres

• 60 square centimetres

• 20 square centimetres

• 40 square centimetres

Answer explanation

The area of a triangle is calculated using the formula: Area = 1/2 × base × height. Here, Area = 1/2 × 10 cm × 6 cm = 30 square centimetres. Thus, the correct answer is 30 square centimetres.

Calculate the perimeter of a square with a side length of 7 cm.

• 28 cm

• 14 cm

• 21 cm

• 49 cm

Answer explanation

The perimeter of a square is calculated by the formula P = 4 × side length. For a side length of 7 cm, P = 4 × 7 = 28 cm. Therefore, the correct answer is 28 cm.

• 28.26 square metres

• 18.84 square metres

• 9.42 square metres

• 37.68 square metres

Answer explanation

The area of a circle is calculated using the formula A = πr². For a radius of 3 metres, A = 3.14 × (3)² = 3.14 × 9 = 28.26 square metres. Thus, the correct answer is 28.26 square metres.

A rectangle has a perimeter of 24 metres. If the length is 8 metres, what is the width?

• 4 metres

• 6 metres

• 8 metres

• 2 metres

Answer explanation

The perimeter of a rectangle is given by the formula P = 2(length + width). Here, P = 24 m and length = 8 m. Plugging in the values: 24 = 2(8 + width). Simplifying gives width = 4 m.

Find the area of a parallelogram with a base of 12 cm and a height of 5 cm.

• 60 square centimetres

• 30 square centimetres

• 50 square centimetres

• 40 square centimetres

Answer explanation

The area of a parallelogram is calculated using the formula: Area = base × height. Here, Area = 12 cm × 5 cm = 60 square centimetres, making the correct answer 60 square centimetres.

What is the perimeter of an equilateral triangle with each side measuring 9 cm?

• 18 cm

• 27 cm

• 36 cm

• 45 cm

Answer explanation

The perimeter of an equilateral triangle is calculated by adding the lengths of all three sides. For a triangle with each side measuring 9 cm, the perimeter is 9 cm + 9 cm + 9 cm = 27 cm, making the correct answer 27 cm.

Calculate the area of a trapezoid with bases of 8 cm and 5 cm, and a height of 4 cm.

• 26 square centimetres

• 32 square centimetres

• 20 square centimetres

• 18 square centimetres

Answer explanation

The area of a trapezoid is calculated using the formula: Area = 1/2 * (base1 + base2) * height. Here, Area = 1/2 * (8 + 5) * 4 = 26 square centimetres, which is the correct answer.

• 5 metres

• 10 metres

• 15 metres

• 20 metres

Answer explanation

To find the radius, use the formula for circumference: C = 2πr. Given C = 31.4 m and π ≈ 3.14, we have 31.4 = 2 × 3.14 × r. Solving for r gives r = 5 m, which is the correct answer.

What is the area of a rhombus with diagonals measuring 10 cm and 8 cm?

• 40 square centimetres

• 80 square centimetres

• 20 square centimetres

• 60 square centimetres

Answer explanation

The area of a rhombus can be calculated using the formula: Area = (d1 * d2) / 2, where d1 and d2 are the lengths of the diagonals. Here, Area = (10 cm * 8 cm) / 2 = 40 square centimetres.