Find the principal value of: cos-1 (tan 3pi/4) Share with your friends Share 3 Varun.Rawat answered this cos-1tan3π4=cos-1tanπ - π4= cos-1- tanπ4=cos-1-1So, cos-1tan3π4 = cos-1-1We know that ranges of the principal values of cos-1 is 0, π.Let cos-1-1 = θ⇒cos θ = -1⇒cos θ = cos π⇒θ = π ∈0, πSo, principal value of cos-1tan3π4 = π 4 View Full Answer
