Identities in Trigonometry
A right angled triangle has a hypotenuse,
base and the perpendicular side. Let angle A be the angle
between the base and the hypotenuse.
then
Sin A = perpendicular / hypotenuse
Sin A = perpendicular / hypotenuse
Tan A = (Sin A) / (Cos A) = perpendicular /
base
Sec A = 1 / Cos A
Cot A = 1 / Tan A = (Cos A) / (Sin A)
Cosec A = 1/ Sin A
Certain basic Trignometry identities
applicable to any angle are:
Sin (-A) = - Sin A
Cos (-A) = Cos A
Tan (-A) = - Tan A
Sin2A + Cos2A = 1
1 + Tan2A = Sec2A
1 + Cot2A = Cosec2A