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**furor celtica** Two cylinders of equal radii each have weight W. They are at rest on a smooth slope of inclination A° to the horizontal, the lower of the two cylinders being in contact with a smooth vertical wall as shown in the diagram. Find, giving your answer in terms of W and A°, the magnitude of the force exerted by

a. the slope on the upper cylinder

b. the lower cylinder on the upper cylinder

c. the upper cylinder on the lower cylinder

d. the wall on the lower cylinder

e. the slope on the lower cylinder

OK so the first three are pretty obvious, a.= WcosA°, b.=c.=WsinA°

However I’m having trouble with d.

So d.=(normal contact force exerted on lower cylinder by slope resolved for the horizontal)+(normal contact force exerted on lower cylinder by upper cylinder resolved for the horizontal) = ((WcosA° resolved for the horizontal) + (WsinA° resolved for the horizontal)) = WcosA°sinA° + WsinA°cosA°=2WsinA°cosA°

However, the correct answer is 2WtanA°; where did I go wrong?