**TI83F* AppVariable file 12/24/08, 18:35( GLA214nav AEBBC47F18701C9F73A97D9443ACC13FGLA214.GLA2141  cofunction identity hcofunction identity:Ösin (((Ä)/(2)) - [) = cos [Öcos (((Ä)/(2)) - [) = sin [Ötan (((Ä)/(2)) - [) = cot [ negative angle identity Onegative angle identity:Ösin (-[) = -sin [ Öcos (-[) = cos [ Ötan (-[) = -tan [ Pythagorean identity YPythagorean identity:Öcos^2 [ + sin^2 [ = 1 Ötan^2 [ + 1 = sec^2 [ Öcot^2 [ + 1 = csc^2 [ quotient identity ^quotient identity:Ötan [ = ((sin [)/(cos [)) , cos [  0Öcot [ = ((cos [)/(sin [)) , sin [  0 reciprocal identity yreciprocal identity:Öcsc [ = ((1)/(sin [)),Ösin [  0.Ösec [ = ((1)/(cos [)),Öcos [  0.Öcot [ = ((1)/(tan [)),Ötan [  0 trigonometric equation ‹trigonometric equation:ÖAn equation containing at least one trigonometric function thatis true for some but not all values of the variable. trigonometric identitystrigonometric identity:ÖAn equation involving a trigonometric function that is true for all values of the variable.žF