What is the required h for equilibrium in a body with two center of masses?

[Axe199]

Homework Statement

problem attached

Homework Equations

The Attempt at a Solution

i had no problem with part i and ii , iii on the other hand, i simply don't know what i should do , i figured out that the required h will be the one making the center of mass of the whole body on the vertical from the point it's standing on ( moments from both center of masses will be equal )
but i have no idea how to get that

 

[NascentOxygen]

The CoM of two combined bodies? http://www.sparknotes.com/physics/linearmomentum/conservationofmomentum/section1.rhtml

"Immediately topples", I think means the cone is lifted clear and the curved surface of the cylinder now rests on the horiz plane.

 

[nvn]

Axe199: It is just geometry and trigonometry, and the moment summation you mentioned in post 1 ... and algebra. And arithmetic. Just start by drawing and labeling the trigonometry; any and everything you know. Eventually, you will build relationships, and be able to write expressions. Just start, and try something. If you do not try something, and do not make a valid attempt, then we cannot check your math and give you hints on where you went wrong.