Half-angle formulas give us another way to find exact values of angles that AREN'T on the Unit Circle!
Source: Created by Crystal Kirch using Camtasia for Mac
more half-angles...
Source: Created by Crystal Kirch using Camtasia for Mac
And another one...
Source: Created by Crystal Kirch using Camtasia for Mac
One last example...
Source: Created by Crystal Kirch using Camtasia for Mac