#### Trigonometry

**BEARINGS**

- The bearing of a point B from another point A is:
- an angle measured from the north at A.
- in a clockwise direction.
- written as a three-figure number (i.e., 000° to 360°)
- For example, the bearing of B from A is 050°

**PYTHAGORAS THEOREM**

- To find the hypotenuse, c: c
^{2}= a^{2}+ b^{2} - To find one of the shorter sides:
- a
^{2}= c^{2}– b^{2} - b
^{2}= c^{2}– a^{2}

- a

- Angle of elevation: is the angles above the horizontal line.
- Angle of depression: is the angle below the horizontal line.

- Area of a triangle =
^{ab}/_{2}sin c

**Ratios**- Right angled Triangles:
- sin x =
^{opposite}/_{hypotenuse}[SOH] - cos x =
^{adjacent}/_{hypotenuse}[CAH] - tan x =
^{opposite}/_{adjacent}[TOA]

- sin x =

- Right angled Triangles:

**Sine Rule**^{a}/_{sin a}=^{b}/_{sin b}=^{c}/_{sin c}- One pair of information needed.

**Cosine Rule**- To find the angle when given 3 sides: cos a =
^{(b2 + c2 – a2)}/_{2bc} - To find a side when given the angle and two sides: a
^{2}= b^{2}+ c^{2}– 2bc cos a

- To find the angle when given 3 sides: cos a =