Half Angle Identities Formula

Equation for calculate half angle identities is,

Half angle equations:
sin(θ / 2) = ± √[1 - cosθ] / 2
cos(θ / 2) = ± √[1 + cosθ] / 2
tan(θ / 2) = ± √[1 - cosθ] / [1 + cosθ]