The solution to problem from the 5th-grade mathematics textbook by E.A. Bunimovich (from the "Spheres" series) involves identifying types of triangles based on their angles or sides. Problem Condition

Does your textbook show specific degree measurements for these triangles, or

Three lines meet in a lonely dance,Joined at corners, by some chance.If one stands tall, a perfect square,A triangle is standing there.

The triangles are classified as follows: