Math by Grades

Math by Topics

$Math Word Problems$

$Probability$

$Set Theory$

Math Worksheets $Math Worksheets$

Math for Specific Tests $SAT Math$
$ACT Math$
$GMAT Math$
$GRE Math$
$High School, Regents$

Math Fun and Games $Math Trivia$
$Math Games$

Exam Preparation

Math in Video Lessons $Basic Algebra$

$Engineering Math$
$Singapore Math$
Science

Others

$What's New$

Triangles

A series of free High School Geometry Video Lessons from Brightstorm.

Triangle Angle Sum
The sum of the three angles in any triangle sum to 180 degrees. The importance of this fact in Geometry cannot be emphasized enough. The triangle angle sum theorem is used in almost every missing angle problem, in the exterior angle theorem, and in the polygon angle sum f

Isosceles Triangle
Isosceles triangles have at least two congruent sides and at least two congruent angles. The congruent sides, called legs, form the vertex angle. The other two congruent angles are the base angles. Isosceles triangles are used in the regular polygon area formula and isosceles right triangles are known as 45-45-90 triangles.

Triangle Side Inequalities
The triangle inequality theorem states that the sum of any two sides of a triangle must be greater than the length of the third side. To find a range of values for the third side when given two lengths, write two inequalities: one inequality that assumes the larger value given is the longest side in the triangle and one inequality that assumes that the third side is the longest side in the triangle. Combine the two inequalities for the final answer.

Triangle Side and Angle Inequalities
In any triangle, the largest angle is opposite the largest side (the opposite side of an angle is the side that does not form the angle). The shortest angle is opposite the shortest side. Therefore, the angle measures can be used to list the size order of the sides. The converse is also true: the lengths of the sides can be used to order the relative size of the angles. Triangle side and angle inequalities are important when solving proofs.

Remote Interior Angles
If one side of a triangle is extended beyond the vertex, an exterior angle is formed. This exterior angle is supplementary with its adjacent, linear angle. Since the angle sum in a triangle is also 180 degrees, the exterior angle must have a measure equal to the sum of the remaining angles, called the remote interior angles.

Custom Search

We welcome your feedback, comments and questions about this site - please submit your feedback via our Feedback page.

Custom Search

Amazon.com Widgets