Created by rory.examtime
almost 6 years ago


The sine rule is a trigonometric rule which is true for all triangles.
The sine rule states that, in the above triangle abc:
SinA = SinB = SinC a b c
This rule is very useful if you know 3 pieces of information about a triangle, and need to find a fourth. For example:
To find x, we can use the sine rule:
Sin(x) = Sin54 4 9
Sin(x) = 4Sin54 9
Sin(x) = 0.3596
x = 21.073
There are 2 conditions necessary for the sine rule to be useful:
We must know at least 3 pieces of information (sides/angles). We must know at least 1 corresponding side/angle pair*.
*e.g if we know angle A, side length b and angle C, the sine rule won't help us.
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