The smooth disks D and E have a weight of 200 lb and 100 lb, respectively. If a horizontal force of P = 200 lb is applied to the center of disk E, determine the normal reactions at the points of contact with the ground at A, B, and C.

Draw the free body diagram.
Consider
,
, and
to be the reaction forces at
,
, and
respectively.
Calculate the angle
.
Calculate the horizontal distance between the two circle centers by using Pythagoras theorem.
Consider the force equilibrium equation in the
direction.
Here,
is the applied force.
Substitute
for
.
Therefore, the normal reaction at
is
.
Consider the force equilibrium equation in the
direction.
Here,
and
are the weights of the disks
and
respectively.
Substitute
for
,
for
, and
for
.
…… (1)
Consider the moments about point
.
Substitute
for
,
for
,
for
, and
for
.
Therefore, the normal reaction at
is
.
for
in equation (1).
Therefore, the normal reaction at
is
.