Calculating angles using trigonometric ratios - Tutorial

math tutorials > calculating angles of a triangle using trig ratios


The size of an unknown angle in a right-angled triangle can be calculated using the trigonometric ratios. 

What you will need:

You will need to use the INV / Shift / 2ndf key on your scientific calculator.



  1. Label the sides.
  2. Identify which trig. ratio uses these sides.
  3. Calculate the angle.

Calculating angles with trig ratios


Trigonometry ratios


Trigonometry problems for you to try.


Problems with triangles, angles and trigonometry