LAdder

Use constraint.

CONSIDER WALL AS +Y AXIS & GROUND AS X AXIS
AS LENGTH OF LADDER IS CONSTANT
x^2+y^2=l^2
differentiate with respect to time
2x\frac{dx}{dt}+2y\frac{dy}{dt}=0
2xv_{x}+2yv_{y}=0
xv_{x}+yv_{y}=0
again differentiate w.r.t time
xa_{x}+ya_{y}+v_{x}^2+v_{y}^2=0
from this eqn find accelerations of both ends
after finding acceleration find their components perpendicular to rod

my calculation give angular acceleration \alpha =\frac{4}{26-9\sqrt{3}}