Trigonometry is used to work out the length of the sides of a triangle or the size of angles in triangle. To work it out you need to know which formula to use.
The 3 formula are :
sin = opposite / hypotenuse
cos = adjacent / hypotenuse
tan = opposite / adjacent.
Hypotenuse is the longest side
Opposite is opposite to the angle being worked out
Adjacent is next to the angle being worked out.