Triangle

\(\text{Area} = \dfrac{1}{2} \times b \times h\)

\(b\) is the length of the base, and \(h\) is the height of the triangle.

Square

\(\text{Area} = s^2\)

\(s\) is the side-length of the square.

Rectangle

\(\text{Area} = b \times h\)

\(b\) is the base (or length) of the rectangle.

\(h\) is the height of the rectangle.

Parallelogram

\(\text{Area} = b \times h\)

\(b\) is the base (or length) of the parallelogram.

\(h\) is the height of the parallelogram.

Trapezium

\(\text{Area} = \dfrac{1}{2}(a + b) \times h\)

\(a\) and \(b\) are the parallel sides of the trapezium.

\(h\) is the height of the trapezium.

Circle

\(\text{Area} = \pi r^2\)

\(r\) is the radius of the circle.

Sector

\(\text{Area} = \dfrac{1}{2} \times r^2 \times \theta\)

Note: for this to work, the angle must be measured in radians

Here, \(r\) is the radius and \(\theta\) is the angle at the centre, in radians.

Ellipse

\(\text{Area} = \pi ab\)

\(a\) and \(b\) are half the lengths of the axes of the ellipse.

What is the area of this rectangle?

Solution: The base has length \(8\) m, and the height is \(4\) m, so the area is

What is the area of this triangle?

Solution: The base has length \(7\) cm, and the height is \(3\) cm, so the area is

What is the area of this trapezium?

Solution: The parallel sides have lengths \(4\) m and \(7\) m, and the height is \(2\) m, so the area is