### Why is the total value of the angles of triangles 180°?

## Why is the total value of the angles of triangles 180°?

The total value of internal angles of all triangles, no matter what type, equals to 180°; let’s try and prove why this is the case. Before the proof, we must remember the angles of two parallel lines at intercepts.
The angles that are formed when two parallel lines intersect are equal to each other. The intersecting line continues to cut the lines and comes towards the other parallel line.

Let’s create a similar system for a triangle;

Let’s create a triangle, showing the angles in different colors, and draw a line parallel to the base.

Now let us look at the situation of the angles and carry out the ‘moving’ operation.

Let’s focus at the very top, the blue, yellow and red angles show the total value of the angles. Since the horizontal line has an angle of 180°, the total value of the angles in a triangle is equal to 180°

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