Finding Base Angles In An Isosceles Triangle

A triangle with two equal sides and a 40° vertex angle is shown, highlighting how the two base angles must be equal. The animation uses the triangle angle sum of 180° to subtract the known angle and split the remainder evenly, revealing each base angle as 70°. It visually reinforces why equal sides produce equal opposite angles, helping students connect algebraic angle equations with geometric symmetry in isosceles triangles.

Narrated · 16:9 · Preview before teaching · automatic layout checks do not establish subject accuracy

The prompt that made it

An isosceles triangle has two equal sides. The angle between those sides measures 40°. What is the measure of each of the other two angles? Color Scheme: #17271F #101B16 #5E6961 #D6EE59 #F5F6F1 #D9DFD3 Use lighter color for background. Audience: 13-18

Make your own version

Make the next one in this series

• Show why equal sides always produce equal opposite angles in any isosceles triangle.
• Animate solving for a base angle when the vertex angle is unknown instead.
• Compare isosceles and equilateral triangles to show how angle sums differ and relate.