## Section outline

- Mensuration
### Mensuration

#### Area of Plane Shapes

Teachers can place simple text and images in a table to explain geometry.

TriangleArea = ½ × b × h

b = base

h = vertical height

SquareArea = a

^{2}a = length of side

RectangleArea = w × h

w = width

h = height

ParallelogramArea = b × h

b = base

h = vertical height

**Trapezium**Area = ½(a+b) × h

h = vertical height

CircleArea = π × r

^{2}Circumference = 2 × π × r

r = radius

**Ellipse**Area = πab

**Sector**Area = ½ × r2 × θ

r = radius

θ = angle in radians

#### Questions can also be posted directly on the page

#### Q1

The diagram shows a circle inside a semicircle.

The circle has a diameter of 20 cm.

The semicircle has a diameter of 40 cm.

Calculate the shaded area. Round your answer to 1 decimal place.

#### Q2

The diagram shows a triangle ABC.

AB = 8 m, AC = 7 m and BC = 9 m.

a) Work out the size of angle B.

b) Work out the area of triangle ABC.

Give your answers correct to 1 decimal place.

#### Answers can be hidden in a collapsed section of the page (click to open)