1.Let a^\hat{a}a^, b^\hat{b}b^, c^\hat{c}c^ be three unit vectors such that a^+b^+c^\hat{a} + \hat{b} + \hat{c}a^+b^+c^ is also a unit vector. If pairwise angles between a^\hat{a}a^, b^\hat{b}b^, c^\hat{c}c^ are θ1\theta_1θ1, θ2\theta_2θ2 and θ3\theta_3θ3 respectively, then cosθ1+cosθ2+cosθ3\cos\theta_1 + \cos\theta_2 + \cos\theta_3cosθ1+cosθ2+cosθ3 equalsa.333b.−3-3−3c.111d.−1-1−1Login to continueOnly logged in users canattempt or see the solution.
