Fundamental Trig Identity 1: http://youtu.be/QixJStd5xAc
Fundamental Trig Identity 2 example 1: http://youtu.be/Qe71jy4B_MM
Fundamental Trig Identity 3 example 2: http://youtu.be/KB3JAEgrmHA
Reference Angle: Definition and how to find it: http://youtu.be/UtvzDPqhcnc
Reference Angle 2: Examples finding Trig values using ref angles: http://youtu.be/hTafPC5rvoE
Reference Angle 3: More Examples finding Trig values using ref angles: http://youtu.be/cljpKceNbR4