## Trigonometry - Right Angled Triangles - Finding a Side

There are three basic formulae, involving the ratio of the lengths of the sides. Given a right angled triangle, we first label the sides for the angle we have:

 If we have the angle shown, we labelthe sides for this angle.Opposite =is the side opposite the angle xHypotenuse =is the longest side, alwaysopposite the right angle.Adjacent=a is the remaining side/We are to calculateWe use one of the formulae We choose which formula to use depending on which side we gave got and which side we need to find. In this case we haveand need to findso we use the formula Example:Now we haveand want to findWe use theformula Example:Now we haveand want to findWe use the formula Example:We have o and want to find h. We use the formulaIt is important to realise the difference between the formulae andFor the first we writebut for the second we actually work out