Let's solve the following tasks:
Task 1: How many triangles are there in the picture?
Step 1
We count how many segments the side of the triangle is divided into, numbering each segment - 1,2,3, etc.
Step 2
We add up all the recorded numbers and thus get the number of triangles searched for.
Answer: 3
Task 2: How many triangles are there in the picture?
Step 1
We count how many small triangles there are in the picture.
Step 2
We add 1 for the big triangle.
Answer: 5
* Triangle counting problems can be found in the course Competitive Mathematics - Level 2