# Videos

Choose from over 80 mathematical videos.

Our team of top teacher mathematicians have put together all the important topics and explain them with the types of examples that you would find in a normal textbook or exam.
• #### Solving Inequalities

This video explains linear and quadratic inequalities and how they can be solved both algebraically and graphically. It includes information on inequalities in which the modulus symbol is used.
Length: 26 minutes

This video is about the solution of quadratic equations. These take the form ax2+bx+c = 0. We will look at four methods: factorisation, completing the square, using a formula, and solution using graphs.
Length: 50 minutes
• #### Solving Trigonometric Equations

Trigonometric equations. The strategy we adopt in solving trigonometric equations is to find one solution using knowledge of commonly occurring angles and then use the symmetries in the graphs of the trigonometric functions to deduce additional solutions.
Length: 44 minutes
• #### Substitution & Formulae

In mathematics, engineering and science, formulae are used to relate physical quantities to each other. They provide rules so that if we know the values of certain quantities, the values of others can be calculated. This video looks at several formulae and how they are used.
Length: 20 minutes
• #### Surds

Roots and powers are closely related, but some roots can be written as whole numbers. These are known as Surds. This video looks at how you can manipulate surds, simplify expressions involving surds and rationalising expressions involving surds.
Length: 33 minutes
• #### Tangents and Normals

Tangents and normals. This unit explains how differentiation can be used to calculate the equations of the tangent and normal to a curve. The tangent is a straight line which just touches the curve at a given point. The normal is a straight line through the point perpendicular to the tangent.
Length: 31 minutes

The addition formulae. There are six so-called addition formulae often needed in the solution of trigonometric problems. In this unit we start with one and derive a second. Then we take another one as given and derive a second one from that. Finally we use these four to help us derive the final two.
Length: 27 minutes
• #### The Chain Rule

The chain rule. This is a special rule that may be used to differentiate a composite function (that is, a function of another function).
Length: 24 minutes
• #### The Double Angle Formulae

The double angle formulae. Double angle formulae are so called because they involve trigonometric functions of double angles e.g. sin 2A, cos 2A and tan 2A.
Length: 26 minutes
• #### The Geometry of a Circle

The geometry of a circle. In this unit the equation of a circle is found from the co-ordinates of its centre and its radius. There are two different forms of the equation. The unit also covers some examples involving tangents to circles.
Length: 40 minutes