acute triangle
acute-angled triangle

For a given acute triangle determine the inscribed triangle of minimal perimeter.

They are often shaped in an acute isosceles triangle with the two equal corners rounded and the third corner rounded to a lesser extent.

Needham's area is roughly in the shape of an acute, northward-pointing triangle.

An acute triangle has angles that are all less than 90 degrees (acute angles)

It appears to widen into a narrow fan, an acute triangle of red light whose base encompasses all of Y.T.'s torso.

What is the chance that three random points in the plane form an acute (rather than obtuse) triangle?

A triangle that has all interior angles measuring less than 90 is an acute triangle or acute-angled triangle.

Thus for acute and right triangles the feet of the altitudes all fall on the triangle.

The orthic triangle of an acute triangle gives a triangular light route.

For example, the dual of a highly acute isosceles triangle is an obtuse isosceles triangle.