^{-1}, cos

^{-1}, and tan

^{-1}) allow you to find the measure of an angle in a right triangle. All that you need to know are any two sides as well as how to use SOHCAHTOA.

### Inverse SOHCAHTOA Way vs Interior Angle Sum

Compare This Method To the tried and true theorem that the sum of the interior angles of a triangle is 180°.

What is the degree measure of LNM?

Since the total measure of the interior angles of a triangle is 180 degrees we can verify the measure of LNM

180° -16° - 90° =74 °

Alternately, you could use the inverse of one of the SOHCAHTOA functions, in this case the inverse of sine (sin^{-1})! To find, an angle of a right triangle all that we need to know is the length of two sides! Then use the same SOHCAHTOA ratios --just in a different fashion See the example below.

^{-1}(73.24/76.19) = 74°

### YouTube Vid: How to Calculate Inverse SOHCAHTOA

A good video on how to use your TI-Graphing Calculator to calculate the inverse sine,cosine or tangent.

Want to buy a TI Graphing Calculator ?