1. The problem statement, all variables and given/known data Which equation is valid only when the angular measure is expressed in radians? a) α = Δθ / Δt b) ω= Δω / Δt c) ω^2 = ωo^2 + 2αθ d) ω = Vt/r (here T is a subscript) e) θ = 1/2αt^2 + ωαt Answer is D but why?? 2. Relevant equations 3. The attempt at a solution a) α = Δθ / Δt Can we please go over each option? OK looking at option a, it does give me an alpha so I don't know what to think of this. Then it says (Alpha = Change of angle/change in time). This seems to be the formula for "angular velocity" but what is alpha? can we go over this first? what is alpha?