The angles of the triangle are 46°, 51°, and 83°. To determine the type of triangle, we can categorize it based on its angles:
- An acute triangle has all angles less than 90°.
- A right triangle has one angle that equals 90°.
- An obtuse triangle has one angle that is greater than 90°.
Since all the angles in this triangle are less than 90°, it is classified as an acute triangle.
So, the correct answer is: acute triangle.