In this module, you can study how to use trig ratios (sine, cosine and tangent) to find an unknown side length or unknown angle measure in a right triangle.
To find the unknown angle measure, you have to use 'inverse' sine, cosine or tangent.
These are the buttons on your calculator: 
(You may need to press 'SHIFT' first to get these.)
A 'TOA' example from the second video:
On a calculator, type:
SHIFT tan ( 3 / 4 ) =
On a different calculator, you may type:
SHIFT tan ( 3 ÷ 4 ) =
or 
( 3 ÷ 4 ) =
The answer you should get is: 36.9
Study and practice
