:TRIG IDs : :1.Sum & Difference :2.Double-Angle :3.Var of Dbl-Angle :4.Half-Angle :5.Pathagorean IDs :6.Even-Odd IDs : : :1.Sum & Difference :cos(+)= :coscos-sinsin :cos(-)= :coscos+sinsin :sin(+)= :sincos+cossin :sin(-)= :sincos-cossin :tan(+)= :(tan+tan)/(1-tantan) :tan(-)= :(tan-tan)/(1+tantan) : :2.Double-Angle :sin(2)=2sincos :cos(2)=cos-sin :cos(2)=1-2sin :cos(2)=2cos-1 :tan(2)=(2tan)/(1-tan) : :3.Variations of :Double-Angle :sin=(1-cos(2))/2 :cos=(1+cos(2))/2 :tan=(1-cos(2))/(1+cos(2)) : :4.Half-Angle :sin/2=(1-cos)/2 :cos/2=(1+cos)/2 :tan/2=(1-cos)/(1+cos) :Variation: sq root right side and remove on left : :5.Pathagorean IDs :sin + cos = 1 :tan + 1 = sec :1 + cot = csc : :6.Even-Odd IDs :sin(-) = -sin :cos(-) = cos :tan(-) = -tan :csc(-) = -csc :sec(-) = sec :cot(-) = -cot