Brilliant
Courses
Practice
Algebra
Geometry
Number Theory
Calculus
Discrete Mathematics
Counting
Sets and Partitions
Data
Probability
Random Variables
Binomial Theorem
Recurrence Relations
Advanced Discrete
Basic Mathematics
Logic
Classical Mechanics
Electricity and Magnetism
Computer Science
Quantitative Finance
Chemistry
Community
Sign up
Log in
Excel in math and science
Master concepts by solving fun, challenging problems.
It's hard to learn from lectures and videos
Learn more effectively through short, interactive explorations.
Used and loved by over 6 million people
Learn from a vibrant community of students and enthusiasts,
including olympiad champions, researchers, and professionals.
Log in with Facebook
Log in with Google
or
Log in with email
Join using Facebook
Join using Google
or
Join using email
New user?
Sign up
Existing user?
Log in
Excel in math and science
Master concepts by solving fun, challenging problems.
It's hard to learn from lectures and videos
Learn more effectively through short, interactive explorations.
Used and loved by over 6 million people
Learn from a vibrant community of students and enthusiasts,
including olympiad champions, researchers, and professionals.
Your answer
seems reasonable.
Find out if you're right!
Sign up to access problem solutions.
That seems reasonable.
Find out if you're right!
Log in with Facebook
Log in with Google
or
Log in with email
Join using Facebook
Join using Google
or
Join using email
New user?
Sign up
Existing user?
Log in
Discrete Mathematics
Discrete Mathematics Warmups
Intro
Concept Quizzes
Rearranging Blocks
Counting Triangles
Quadruplets Ordering
Arrangement Puzzles
Recursion
Walking in a Rectangular Grid
Challenge Quizzes
Level 1
Level 2
Level 3
Level 4
Level 5
Counting Triangles Warmup
How many triangles can you find in this figure?
6
5
7
4
Submit
How many triangles can you find in this figure?
8
6
3
12
Submit
How many triangles can you find in this picture?
12
13
18
9
Submit
How many triangles can you find in this figure?
16
10
14
20
Submit
How many triangles can you find in this figure?
4
3
5
6
Submit
×
Problem Loading...
Note Loading...
Set Loading...