Why do the angles in a triangle add up to 180°??

What is a Right Triangle? | Types of Triangles | Math with Mr. J

Right Angled Triangle: Find Angles - Trigonometry - VividMath.com

Math Antics - Triangles

Proof of the Sum of Angles of a Triangle Measure 180 Degrees | Don't Memorise

Triangle Song | Types of Triangles Song | Classifying Triangles

How to Determine Whether a Triangle is a RIGHT Triangle

Why do exterior angles of any polygon add up to 360°?

largest isosceles triangle in a circle

Trigonometry: Solving Right Triangles... How? (NancyPi)

Finding the Missing Angle of a Triangle: A Step-by-Step Guide | Triangles | Math with Mr. J

Proof: Sum of measures of angles in a triangle are 180 | Geometry | Khan Academy

Trigonometry - How To Solve Right Triangles

How to find a missing angle in a right angled triangle

Angles Song | Acute, Obtuse, & Right Angles | 3rd & 4th Grade

Proving the Interior Angles of a Triangle Add Up to 180 Degrees

Use Pythagoras to decide if a triangle is right-angled

CALCULATING RIGHT ANGLE TRIANGLES

Area and Perimeter of a Right Triangle | Math with Mr. J

Learn to find the missing angles for a triangle using inverse trig functions