Let \({ }^{n} {C}_{r-1}=28,{ }^{n} {C}_{r}=56\) and \({ }^{n} {C}_{r+1}=70\). Let \(A(4 cos\ t, 4 sin \ t), {B}(2 sin \ t,-2\) cos t) and \({C}\left(3 r-n, r^{2}-n-1\right)\) be the vertices of a triangle ABC, where t is a parameter. If \((3 x-1)^{2}+(3 y)^{2}=\alpha\), is the locus of the centroid of triangle ABC, then \(\alpha\) equals
Consider a trapezoid ABCD, one of whose non parallel sides AB which is 8 cm long is perpendicular to the base. The base BC and AD of trapezoid are 6 cm and 10 cm in lengths respectively. Let \(L_1, L_2, L_3, L_4\) represent the lines AB, BC, CD and DA respectively and \(d(P, L)\) denote the perpendicular distance of point P from line L.Find the area of region inside the trapezoid ABCD in which the point Q can lie satisfying \(d(Q, L_4) \leq d(Q, L_3)\):