Geometry: Triangles (the basics)

Triangle Angle Sum Theorem

the sum of the three interior angles in any triangle is always 180°.

Acute Triangle

all three angles are less than 90°.

Obtuse Triangle

a triangle that has one angle greater than 90°.

Right Triangle

a triangle that has one angle exactly equal to 90°.

Scalene Triangle

Triangles with all sides and all angles of different lengths and measures.

Isosceles Triangle

Triangles that have two sides of equal length and two equal angles.

Equilateral Triangle

three equal sides and three equal angles, with each angle measuring 60°