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Maths I

Trigonometry

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Introduction

Trigonometry is often abbreviated to trig

In a right angled triangle, the side opposite the right angle is called the hypotenuse.

If one of the other angles is x°, then we can label the remaining sides as shown in this diagram.

Always remember to label the sides of the triangle.

A right angled triangle. Thebottom angle that isn't 90 degrees is labelled x degrees. The longest edge is labelled hypotenuse, the vertical edge is labelled opposite to x degrees, the horizontal edge is labelled adjacent to x degrees. From x degrees there radiates two arrows, one pointing to the opposite and one pointing to the adjacent.

There are 3 trig ratios you need to know:

  • sine
  • cosine
  • tangent

We shorten these to:

  • sin
  • cos
  • tan

A right angled triangle. The longest edge, across from the right angle, is labelled hypotenuse, the edge acoss from the angle marked x degrees is called opposite, and the bottom edge is called adjacent

sin x° = opposite/hypotenuse

cos x° = adjacent/hypotenuse

tan x° = opposite/adjacent

This is printed on page 2 of your General paper. Remember to look for it.

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