Sorting by Sides
Part of the Triangles section of Coddy's Geometry journey. Lesson 2 of 63.
Triangles are sorted by how many of their sides are equal. An equilateral triangle has all three sides equal. An isosceles triangle has (at least) two equal sides. A scalene triangle has no two sides equal.
A figure shows equal sides with small tick marks: sides with the same number of ticks are equal. Lengths written on the sides tell you the same thing. As with angles, never judge by eye: a triangle can look isosceles and be scalene.
Here BC and CA both carry two ticks, so they are equal and △ABC is isosceles. The base AB has no ticks, so it may have any length.
Challenge
Three triangles have their side lengths written on them. Tap the scalene triangle, then press Check.
Try it yourself
Find the right part on the figure
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Triangles
1Sides and Names
Three Sides, Three CornersSorting by SidesNaming by AnglesTicks into EquationsThe Longest SideRecap: Sorting Triangles2The Triangle Inequality
Can Three Sticks Meet?Exactly ReachingThe Range of the Third SideThe FormulaRecap: The Third Side5The Pythagorean Theorem
Squares on the SidesFinding the HypotenusePythagorean TriplesWhen It Is Not WholeRecap: The Hypotenuse3Perimeter
Around the EdgeA Missing SideIsosceles PerimeterSides as ExpressionsRecap: Around the Edge6Finding a Leg
Working BackwardsThe LadderWhich Side Is c?A Leg That Is Not WholeRecap: Finding a Leg