write principal value of: (cos-1root3/2 +cos-1(-1/2)) Share with your friends Share 1 Manbar Singh answered this We know that, range of the principal values of cos-1 is 0,π.Let cos-132 = α⇒cos α = 32⇒cos α = cosπ6⇒α =π6∈ 0,π.Let cos-1-12 = β⇒cos β = -12⇒cos β =-cosπ3⇒cos β = cosπ-π3⇒cos β = cos2π3⇒β = 2π3∈ 0,π.Now, cos-132 + cos-1-12 = π6+2π3 = 5π6 3 View Full Answer