None because no triangle has any parallel sides.
None but all three sides are equal in length.
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None, two or three
Every triangle must have at least 2 acute angles, otherwise it is impossible to make the 3 sides connect.
First: Sides are not acute or obtuse. ANGLES are acute or obtuse. An acute triangle has to have all angles acute. Examples: 60, 60, 60 70, 60, 50 45, 50, 85 45, 45. 90 30, 60, 90 But if one of the angles is obtuse (>90 degrees), then the other two must be acute. Of course, *this* triangle would not be called an acute triangle, because one of its angles is abtuse; it would be called an obtuse triangle.
There are absolutely 0 parallel lines in any given triangle.
In an acute triangle, all three angles are acute.
In a regular nonagon no two sides are parallel.
An acute scalene triangle has none. An acute isosceles triangle has one and an [acute] equilateral has three.
there are three acute angles in an acute triangle, because there are three corners.
There are three acute angles in an acute triangle and they add up to 180 degrees.
Sides cannot be acute.