The bisector of angle B of parallelogram ABCD intersects side AD at point N. Find the perimeter of the parallelogram

The bisector of angle B of parallelogram ABCD intersects side AD at point N. Find the perimeter of the parallelogram if AN = 2.5cm, ND = 12.5cm

1) Side AD = AN + ND
AD = 2.5 + 12.5 = 15 cm
2) angle ANB = angle CBN, as crosswise lying angles with AD parallel BC with secant BN, but angle CBN = angle ABN by condition, since BN is a sectrix, hence angle ANB = angle ABN, hence triangle ABN is isosceles and AB = AN = 2.5
3) P = 15 * 2 + 2.5 * 2 = 35 cm
Answer: 35 cm