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A pendulum constituted of a rope of the length $l$ and a body is displaced from it's equilibrium. The force due to gravity on the body $F_g=20\mathrm{N}$. The body is higher by $h=10\mathrm{cm}$ in the displaced position (comparing to the equilibrium position). The tension in the rope in the displaced position is $F_1=12\mathrm{N}$. Find the length of the rope $l$. Hint: Using a parallelogram, the force of gravity on the body can be decomposed into a force $F_1$ in the direction of the rope and $F_2$ in the perpendicular direction.