When you're learning about triangles and the Pythagorean Theorem, there's a neat way to understand how they are classified based on their angles. Let's break it down:

• Right Triangles: This type of triangle has one angle that is exactly $90^\circ$. This is a right angle. You can use the Pythagorean Theorem here, which says $a^2 + b^2 = c^2$. In this equation, $c$ is the longest side, called the hypotenuse. This rule helps you figure out if a triangle is a right triangle.

• Acute Triangles: All the angles in an acute triangle are smaller than $90^\circ$. To tell if it's an acute triangle, you can check the lengths of the sides. If the sum of the squares of the two shorter sides is more than the square of the longest side, it’s an acute triangle. This means $a^2 + b^2 > c^2$.

• Obtuse Triangles: In an obtuse triangle, one angle is bigger than $90^\circ$. For these triangles, the opposite is true: $a^2 + b^2 < c^2$.

So, by using the Pythagorean Theorem, you can easily tell the difference between these types of triangles!