Triangles

Facts:

• A triangle is a polygon with three sides.
• It also has three angles.
• The sum of all three angles is 180 degrees.
• An equilateral triangle has three sides that are the same length.
• An isosceles triangle has two sides of the same length.
• A scalene triangle has three sides that are all different lengths.

Special types of triangles:

• 30-60-90 right triangles
• 45-45-90 right triangles
• 3-4-5 triangle

Related Lessons/Formulas

• Pythagorean Theorem
• Law of sines
• Law of cosines