To determine the type of triangle, we will find the value of the third angle and compare them.
The sum of the angles of the triangle is 180, then the angle KNM = 180 – MKN – KMN = 180 – 18 – 81 = 81.
Since a triangle has two angles equal, it is an isosceles triangle with base KN and lateral sides MN and MK.
Answer: the triangle is isosceles.
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