### Теория:

Let's learn the types of triangle:
Triangles can be classified based on its sides as well as its angles.
Types of triangles based on its side lengths are as follows.
• Equilateral triangle
• Isosceles triangle
• Scalene triangle
A triangle is an equilateral when all its sides are equal in length.

Example:

In here, the sides are equal in measure $$AB=BC=CA=5$$ units.
A triangle is isosceles when two of its sides are equal in length.
Example:
In here, the two of the sides are equal in measure $$AB=CA=1$$ unit and $$BC=√2$$ units.
A  triangle is a scalene when all the three sides are unequal.
Example:
In here, all the sides are unequal in measure $$AB=7.7, CA=5$$ units and $$BC=9$$ units.
Types of triangles based on its angles are as follows.
• Acute angled triangle
• Right angle triangle
• Obtuse angled triangle
A triangle is acute angle triangle when all the three of its angle are acute (less than 90°).
Example:
In here, all the three angles are less than $$90°$$.  That is, $$∠A=60°, ∠B=50°$$ and $$∠C=70°$$.
A triangle is right angle triangle when one of its angles is a right angle (90°), and the other two are acute angles (less than 90°).
Example:
In here, one among the angle is $$90°$$, and the other two are acute. That is, $$∠A=40°, ∠B=50°$$ and $$∠C=90°$$.
A  triangle is an obtuse angle triangle when one of its angles is an obtuse angle (greater than 90°), and the other two are acute angle (less than 90°).
Example:
In here, one among the angle greater than $$90°$$ and the other two are acute. That is, $$∠A=120°, ∠B=35°$$ and $$∠C=25°$$.