If you're seeing this message, it means we're having trouble loading external resources for Khan Academy.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Classifying shapes

8 videos
3 skills
In this tutorial, we'll classify two-dimensional figures based on the presence or absence of parallel or perpendicular lines, or the presence or absence of angles of a specified size. We'll also learn about special triangles called "right triangles". Common Core Standard: 4.G.A.2

Quadrilateral overview

VIDEO 8:24 minutes
"Quad" means "four" and "lateral" means "line." A quadrilateral is literally a shape with four sides (lines) and four angles. Let's learn the difference between concave and convex quadrilaterals as well as trapezoids, parallelograms, and ...

Quadrilateral properties

VIDEO 5:07 minutes
How about this: we are given a 4-sided shape and asked to determine whether its properties qualify it to be called a quadrilateral (or category of quadrilaterals). Check it out.

Quadrilaterals: kites as a geometric shape

VIDEO 5:38 minutes
Is a kite a quadrilateral? Is it a rhombus? A parallelogram? Let's find out.

Quadrilaterals: find the type exercise

VIDEO 2:49 minutes
Take a look at the given data and determine what type of quadrilateral we have.

Quadrilateral types

PRACTICE PROBLEMS

Triangles: categorization by angle or equal sides.

VIDEO 6:00 minutes
Scalene, isosceles, equilateral, acute, right, obtuse. All are types of triangles but what makes them special depends on the method of categorization. Watch this outstanding explanation.

Triangles: using angles to categorize

VIDEO 5:30 minutes
You say you can't categorize a triangle because you don't the length of the sides. Guess what? If you know the size of the angles you can!

Categorizing triangles

VIDEO 2:23 minutes
Let's practice categorizing triangles in this example exercise.

Recognizing triangle types

PRACTICE PROBLEMS

Categorizing geometric shapes: practice examples

VIDEO 2:15 minutes
Watch and do these example exercises along with us. Remember what you have learned about perpendicular lines, right, obtuse, and acute triangles.