Question

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Said quadrangle ABCD for the measurement of the angle A; B; C; D proportional voi5; 8; 13va 10.A / Count measure the angles of a quadrilateral ABCDb / Extend sides AB and DC intersect at E, which lasted two sides AD and BC in F. Two-rays catnhau sense of angles AED and corner cutting AFB O. Separate each corner giaccua AFB cutting edge CD and AB at M and N. Prove cuadoan MN O is the midpoint.