a triangle whose interior angles are all acute

a triangle with a right angle.

a triangle that contains an obtuse interior angle

a three-sided regular polygon

a three-sided regular polygon

a triangle with two equal sides

a triangle with no two sides of equal length

THE SIDE-SIDE-SIDE (SSS) CONGRUENCE STATES THAT IF THE THREE SIDES OF ONE TRIANGLE HAVE THE SAME LENGTHS AS THE THREE SIDES OF ANOTHER TRIANGLE, THEN THE TWO TRIANGLES ARE CONGRUENT.

Side-angle-side (SAS) congruence states that if any two sides of a triangle are equal in length to two sides of another triangle and the angles bewteen each pair of sides have the same measure, then the two triangles are congruent; that is, they have exactly the same shape and size.

Triangles are congruent if any two angles and their included side are equal in both triangles.

Triangles are congruent if two pairs of corresponding angles and a pair of opposite sides are equal in both triangles

CORRESPONDING PARTS OF CONGRUENT TRIANGLES ARE CONGRUENT

When three or more lines meet at a single point, they are said to be concurrent. In a triangle, the three medians, three perpendicular bisectors, three angle bisectors, and three altitudes are each concurrent.

A median of a triangle is a line segment joining a vertex to the midpoint of the opposite side.

The centroid of a triangle is the point where the three medians meet. This point is the center of mass for the triangle. If you cut a triangle out of a piece of paper and put your pencil point at the centroid, you could balance the triangle.

Altitude of a Triangle is the perpendicular distance from any of its vertices to the opposite side. (This opposite side of the vertex is called the base of the altitude.)