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:
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If we have the angle shown, we label the sides for this angle. Opposite = Hypotenuse = opposite the right angle. Adjacent=a is the remaining side/ We are to calculate
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We choose which formula to use depending on which side we gave got and which side we need to find. In this case we have |
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Example: Now we have formula
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Example: Now we have
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Example: We have o and want to find h. We use the formula
It is important to realise the difference between the formulae
For the first we write |
is the side opposite the angle x
is the longest side, always
We use one of the formulae
We use the
and want to find
We use the formula
and
but for the second we actually work out