2006-II-44
Ans: A
$\begin{array}{rcl}
3\cos^2 x -4\cos x +1 & =
… Read $\begin{array}{rcl}
3\cos^2 x -4\cos x +1 & =
Note that each faces of the tetrahedron are equilater
$\begin{array}{ll}
OB=OC & \t
In $\Delta OAB$,
$\begin{array}{ll}
OB = B
$\begin{array}{cl
$\begin{array}{|c|c|c
$\begin{array}{cl}
=