Applied Mechanics and Graphic Statics
The following is in unstable equilibrium

A satellite encircling the earth
A uniform solid cone resting on its base on a horizontal plane
A solid cube resting on one edge
A uniform solid cone resting on a generator on a smooth horizontal plane

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Applied Mechanics and Graphic Statics
According to Law of Triangle of Forces

If three forces acting on a, point can be represented in magnitude and direction, by the sides of a triangle taken in order, these will be in equilibrium
Three forces acting along the sides of a triangle are always in equilibrium
Three forces acting at a point, can be rep-resented by the sides of a triangle, each side being in proportion to the force
If the forces acting on a particle be represented in magnitude and direction by the two sides of a triangle taken in order, their resultant will be represented in magnitude and direction by the third

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