## Before You Watch

This video builds directly on the concepts discussed in Introduction to Trigonometry, which presented the three basic trigonometric ratios: sin, cos and tan. If you haven’t watched the Introduction to Trigonometry video yet, do that first, then come back.

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## Now What?

After watching this video, plus Introduction to Trigonometry, you should be comfortable with finding the length of a side of a right-angled triangle when given the length of another side and an angle of the triangle.

Beyond this, it is recommended that you investigate other applications of trigonometry, such as finding an angle when given the sides of the triangle, or the sine and cosine rules. You can explore these through websites such as https://www.khanacademy.org/math/trigonometry/basic-trigonometry.

Alternatively, you can learn about other algebraic concepts such as Algebraic Fractions or Factorisation of Algebraic Expressions.

## But When I am Going to Use This

The obvious application of trigonometry is for right-angled triangles. This is common in construction, surveying and the application discussed in this video, where things like forces, or movement, are broken down into perpendicular components. However, trigonometry can also extend to non-right angled triangles through, for example, the sine rule and the cosine rule.

Moving beyond triangles, trigonometry is critical to the study of waves, such as radio waves. This is very important in fields such as wireless communication and quantum physics: for instance, mobile phone technology would be impossible without a method of breaking down a signal into a series of sines and cosines known as Fourier Analysis.