TRIGONOMETRY

The Beginning of TrigonometryTrigonometry can be used to calculate the lengths of sides and sizes of angles in right-angled triangles. The three formulas: sin, cos, tanThe sides of the right-angled triangles are given special names - the hypotenuse, the opposite and the adjacent.The hypotenuse is the longest side and is always opposite the right angle. The opposite and adjacent sides relate to the angle under consideration.There are three formulae involved in trigonometry:sin = opposite / hypotenuse cos = adjacent / hypotenuse tan = opposite / adjacent Which formula you use will depend on the information given in the question.There are a couple of ways to help you remember which formula to use. Remember SOHCAHTOA (it sounds like 'Sockatoa') or Some Old Hag Cracked All Her Teeth On Apples.

Cont.SOH- S means sin CAH- C means cos TOA- T means tan O means opposite A means adjacent O means opposite H means hypotenuse H means hypotenuse A means adjacent

Make sure you follow this diagram above. ^^^^

Example

We are given angle A and side AB. AB is the hypotenuse. BC is opposite angle A. Therefore we use the formula: sin = opposite / hypotenuse sin 30 = BC/7 Multiply both sides by 7 7 x sin30 = BC Using a calculator we get BC = 3.5cm

Practice Questions1

2

3

ANSWERS:

1. 4.77cm2. 5.52cm3. 7.15cm

WELL DONE IF YOU GOT THEM ALL RIGHT!

Do you think trigonometry is easy

now?I hope you do because

we understand it.If you have any trouble with trigonometry still just ask us, Nitisha or

Robyn.

Trigonometry can be fun!