# Introduction To SOHCAHTOA | Trigonometry | Maths

Triangles are the building blocks of all other straight-edged shapes.

They were used for hundreds of years to create accurate maps and GPS today still works using trigonometry. Even the pixels on phones and screens use trigonometry.We need to know these things so that we can work out exact lengths of sides of triangles or how big certain angles are in triangles.

There are 3 main functions in trigonometry:

- Sine

- Cosine

- Tangent

These functions are just ratios between sides and angles on right-angle triangles. So we need to firstly know which side is the hypotenuse, which is the opposite and which is the adjacent.

The hypotenuse is the longest side and is always opposite the right-angle.

Then we have the adjacent and the opposite. These change positions depending upon which angle we are using.Here, this side is the opposite because it is opposite the angle and this side is the adjacent because it is next to the angle. But see how when we change the angle, the adjacent and opposite move. Sin cos and tan are just ratios between sides and angles on right-angle triangles.

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