# Trigonometry

## 11 videos in this playlist

Pythagoras' Theorem
Pythagoras' theorem - the square on the hypotenuse is equal to the sum of the squares on the other two sides - is well known. In this tutorial we revise…
Trig Ratios in a Right Angled Triangle
Knowledge of the trigonometric ratios of sine, cosine and tangent is vital in very many fields of engineering, science and maths. This unit introduces them and provides examples of how…
Trig Ratios of an Angle of any Size
Knowledge of the trigonometric ratios sine, cosine and tangent is vital in many fields of engineering, maths and science. This unit explains how the sine, cosine and tangent of an…
Most people usually learn to measure an angle in degrees. But in many scientific and engineering calculations radians are used in preference to degrees.
Trig 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…
Trig Identities
In this unit we consider trigonometric identities and how to use them to solve trigonometric equations.
Trig Functions
A common mathematical problem is to find the angles or lengths of the sides of a triangle when some, but not all, of these quantities are known. It is also…
Cosec, Sec and Cot
In this unit we see how the three trigonometric ratios cosecant, secant and cotangent can appear in trigonometric identities and in the solution of trigonometric equations. Graphs of the functions…
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…
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.
a cos x + b sin x = R cos(x - α)
In this unit we explore how the sum of two trigonometric functions e.g. 3 cos x + 4 sin x, can be expressed as a single trigonometric function. Having the…

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