In the MNKL trapezoid, the diagonal MK is perpendicular to the side of the KL
In the MNKL trapezoid, the diagonal MK is perpendicular to the side of the KL, the angle NMK = KML = 30 degrees. Trapezium perimeter MNKL = 30cm. Find the side of NK
Since the angle NMK = KML = 30, then the angle NML = 30 + 30 = 60.
In a right-angled triangle MKL, the angle KLM = 90 – 30 = 60. Then the angle NMK = KLM = 60, then the trapezoid is isosceles, NM = KL.
Leg KL lies opposite angle 30, then KL = ML / 2.
Let the length MN = KL = X cm, then ML = 2 * X cm.
The sum of the angles of the trapezoid, with the lateral side, is 180, then the angle NKL = (180 – 60) = 120.
Then the angle MKN = 120 – 90 = 30, then the triangle MNK is isosceles, MN = NK = X cm.
Then Рmnkl = X + X + 2 * X + X = 30 cm.
5 * X = 30.
X = NK = 30/5 = 6 cm.
Answer: The length of the NK side is 6 cm.