Choose Sin, Cos or Tan
depending on the sides
we know
In this case COS, as we
have the HYP - 13 and the
ADJ -12
COS(angle) = ADJ/HYP = 12/13
Look up the angle using
the [shift] button on the
calculator
angle= COS^-1(12/13)
22.6
In this case SIN, as
we have the OPP -
15 and the HYP -20
SIN(angle) = OPP/HYP = 15/20
angle= SIN^-1(15/20)
48.6
Using Trig. to find
Missing edges
Label the Triangle that we
know, or are trying to find
Choose SIN, COS or TAN
depending on the edge we
are interested in.
Choose the correct formula and write down the calculation
Type into Calculator
Trigonometry gives us a method for finding missing
edges in right angled triangles when we know one edge
and one angle (in addition to the right angle). We can
also use trig. to find an angle if we know the edges.