In a triangle MNK, the angle M is 18 degrees, and the angle K is 81 degrees. What can you call such a triangle?

The sum of all the angles of any triangle is 180 °.

Find the angle N: 180 ° – 18 ° – 81 ° = 81 °. That is, in the triangle MNK, two angles are equal. This is only possible in an isosceles triangle.

Let’s check the remaining items.

A) Obtuse. No. In this triangle, all angles are less than 90 °, i.e. sharp.

B) Acute angle. Yes. In this triangle, all corners are sharp.

B) Rectangular. No. In a right-angled triangle, one of the angles is 90 °. There are no such corners here.

Answer: isosceles acute-angled triangle.