Acute triangle

Revision as of 14:25, 9 February 2009 by R15s11z55y89w21 (talk | contribs)

An acute triangle is a triangle in which each angle is an acute angle. Any triangle which is not acute is either a right triangle or an obtuse triangle.

Acute triangles can also be defined in different ways:

  • A triangle is acute if and only if each of its altitudes lies entirely in the triangle's interior.
  • A triangle with sides of length $a, b$ and $c$ is acute if and only if $a^2 + b^2 > c^2$, $b^2 + c^2 > a^2$ and $c^2 + a^2 > b^2$. This is known as the Pythagorean Inequality.

An equilateral triangle is always acute. In an acute triangle, the circumcenter, incenter, orthocenter, and centroid are all within the triangle.

This article is a stub. Help us out by expanding it.

Invalid username
Login to AoPS