Triangle Properties

learning_notes

Last updated: 8/16/2025

Key Concepts:

  • Triangle Angle Sum Theorem – The sum of the three interior angles of any triangle is (180°).
    • Sum of Interior Angles of a Polygon with $n$ sides: ((n-2) \cdot 180°)
  • Isosceles Triangle Properties – A triangle with two equal sides has two equal angles opposite these sides.
  • Equilateral Triangle Properties – A triangle with three equal sides has three (60°) angles.
  • Right Triangle Properties – A triangle with one (90°) angle; the two acute angles are complementary.
  • Exterior Angle Theorem – An exterior angle of a triangle is equal to the sum of the two remote interior angles.

Skills Covered:

  • Finding unknown angles in a triangle using the Triangle Angle Sum Theorem.
  • Identifying base angles in an isosceles triangle and solving for missing angles.
  • Applying the Exterior Angle Theorem to find unknown angles in geometric diagrams.

Features

  • Aris - 1on1 AI tutor
  • Skills Tree
  • Improvement analytics
  • Error-Hacking Vault
  • Special topics
logoAris Tutor

ArisTutor is powered by a group of standardized test prep experts from top-tier colleges who aspire to help more students get high-quality ACT, AP and SAT prep resources at a fraction of the cost of premium tutors.

SAT® and AP® are trademarks registered by the College Board, which is not affiliated with, and does not endorse, this product.
ACT® is a trademark registered by the ACT, Inc, which is not affiliated with, and does not endorse, this product.