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mathematicsprinted 104 · PDF 105
165 pagesrevision 46935
printed 104 · PDF 105
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104
The 3 trigonometric functions which you will study at this level are sin(θ),
cos(θ) and tan(θ) where θ is an angle. These functions can only be applied to
right angled triangles to find the values of missing sides and angles. Before
understanding how to apply them, you need to be able to recognise the
different sides of a triangle.
The side opposite to the right angle is always called the hypotenuse. This is
the longest side in a right angled triangle. The names of the other 2 sides
change depending on which angle is being used in the function. For example,
if angle A is being used, the side opposite to that angle will be called opposite.
Once you have labelled the hypotenuse and opposite, the remaining side will
be the adjacent side. If I take into account the angle at the top of the triangle,
the opposite and adjacent sides will be switched.
Sin Opposite Hypotenuse - SOH
𝑠𝑖𝑛(𝜃) =
𝑂𝑝𝑝𝑜𝑠𝑖𝑡𝑒
𝐻𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒
Cos Adjacent Hypotenuse - CAH
𝑐𝑜𝑠(𝜃) =
𝐴𝑑𝑗𝑎𝑐𝑒𝑛𝑡
𝐻𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒
Tan Opposite Adjacent - TOA
𝑡𝑎𝑛(𝜃) = 𝑂𝑝𝑝𝑜𝑠𝑖𝑡𝑒
𝐴𝑑𝑗𝑎𝑐𝑒𝑛𝑡