In parallelogram ABCD, the diagonal AC is the bisector of angle A. Find the perimeter of ABCD if side Ab is side 8.

The angle of the BCA is equal to the angle DАС (internal criss-crossing angles with parallel АD and ВС and secant АС). The angle CAD is equal to the angle CAB (since A is the bisector).

This means that triangle ABC is isosceles (an isosceles triangle has equal angles at the base). Hence, ВA = BC = 8.

In a parallelogram, opposite sides are equal, which means that all sides of the parallelogram are 8, PABCD = 8 * 4 = 32.

Answer: the perimeter of the parallelogram ABCD is 32.



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