### WHAT ARE THE MOST IMPORTANT TRIGONOMETRIC IDENTITIES? The three Pythagorean trig identities 1.Sin2α + Cos2α = 1 2.Sec2α – tan2α = 1, Sec2α = 1+ tan2α 3. Cosec2α – cotan2α = 1, Cosec2α = 1+ cotan2α 6.Trig identities of compound angles 1. sin (A + B) = sinAcosB + cosAsinB 2. sin (A – B) = sinAcosB – cosAsinB 3. cos (A + B) = cosAcosB – sinAsinB 4. cos (A – B) = cosAcosB + sinAsinB 5.Tan(A + B) = (sinAcosB + cosAsinB)/(cosAcosB – SinAsinB) 6.Tan(A – B) = (sinAcosB – cosAsinB)/(cosAcosB…