Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles.

Popular Tutorials in Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles.

How Do You Find a Missing Angle in a Triangle?

Trying to find a missing interior angle measurement in a triangle? Already know the other two interior angle measurements? Then you're set! Just remember that the interior angles of a triangle ALWAYS add up to 180 degrees. This tutorial shows you how to put this knowledge into an equation and solve to find that missing measurement!
How Do You Find Missing Angles in an Isosceles Triangle?

Trying to find a missing interior angle measurement in a triangle? See if you're working with a special type of triangle such as an equilateral or isosceles triangle. If you are, that knowledge can help you. In this tutorial, see how identifying your triangle first can be very helpful in solving for that missing measurement. Take a look!
How Do You Find Missing Angles in a Triangle With Variables?

Looking for the measurements of the interior angles of a given triangle? The Triangle Sum theorem might help. This theorem states that the interior angles of a triangle ALWAYS add up to 180 degrees! This tutorial shows you how to use that information to find those interior angle measurements.
How Do You Find the Angles in a Triangle if You Have a Ratio of Their Measures?

Looking for the measurements of the interior angles of a triangle? Then check out this tutorial! You'll see how to use a given ratio of the interior angles and the Triangle Sum theorem to find those missing measurements. Take a look!
How Do You Find Missing Angles in an Isosceles Triangle Using Right Triangles?

Trying to find a missing interior angle measurement in a triangle? See if you're working with a special type of triangle such as an equilateral or isosceles triangle. If you are, that knowledge can help you. In this tutorial, see how identifying your triangle first can be very helpful in solving for that missing measurement. Take a look!
How Do You Find a Missing Angle in a Right Triangle?

Trying to find a missing interior angle measurement in a triangle? See if you're working with a special type of triangle such as an equilateral or isosceles triangle. If you are, that knowledge can help you. In this tutorial, see how identifying your triangle first can be very helpful in solving for that missing measurement. Take a look!
How Do You Find Missing Angles in a Transversal Diagram?

Got a diagram of a transversal intersecting parallel lines? Trying to figure out all the angle measurements? Take a look at this tutorial, and you'll see how find all the missing angle measurements by identifying vertical, corresponding, adjacent, and alternate exterior angles!
What is a Triangle?

You can't learn everything about math without dealing with triangles. Did you know that there are different types of triangles? Check out this tutorial, and learn about triangles and their different types!
What is a Transversal?

Ever heard of a transversal? It's not as confusing as the term sounds. This tutorial will introduce you to transversals and show you the neat things that happen when a transversal meets two parallel lines. Take a look!
What is the Triangle Sum Theorem?

When you're dealing with triangles, the Triangle Sum theorem can be very useful in finding interior angle measurements. In this tutorial, learn how to find this helpful theorem!