If $P(3,2,6), Q(1,4,5)$ and $R(3,5,3)$ are the vertices of $\Delta PQR$,then $m \angle PQR$ is (in $^{\circ}$)

If the origin is the centroid of the triangle $PQR$ with vertices $P(2a, 2, 6)$,$Q(-4, 3b, -10)$,and $R(8, 14, 2c)$,then find the values of $a, b$,and $c$.

If the origin is the centroid of the triangle $PQR$ with vertices $P(2a, 2, 6)$,$Q(-4, 3b, -10)$,and $R(8, 14, 2c)$,then the values of $a, b, c$ respectively are:

If the vertices of a triangle $ABC$ are $A(1, 2, 3)$,$B(h, -3, 0)$,and $C(-4, k, -1)$ and the centroid of the triangle is $\left(5, -1, \frac{2}{3}\right)$,then triangle $ABC$ is

If $A(1, 2, -3)$,$B(2, 3, -1)$,and $C(3, 1, 1)$ are the vertices of $\triangle ABC$,then $\left|\frac{\cos A}{\cos B}\right| = $

If $G(4, 3, 3)$ is the centroid of the triangle $ABC$ whose vertices are $A(a, 3, 1)$,$B(4, 5, b)$,and $C(6, c, 5)$,then the values of $a, b, c$ are: