A narrow beam of protons with kinetic energy of 100 keV padant normally on gold foil, which pd = 1.0 mg / cm ^ 2 (p - density, d - thickness). The protons scattered at an angle of 60 °, counter registers, input round hole which has an area of 1.0 cm ^ 2, and it is separated from the scattering foil section at a distance of 10 cm. The hole is oriented perpendicular to counter falling on him protons. What proportion of the scattered protons enters the opening of the counter?

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