Find the proper length of a rod if in the laboratory frame of reference its velocity is v=c/2,v=c / 2,v=c/2, the length l=1.00 m,l=1.00 \mathrm{~m},l=1.00 m, and the angle between the rod and its direction of motion is θ=45∘\theta=45^{\circ}θ=45∘