A specific type of plane is called a polygon or polygon. Its sides are straight lines. Also, are all sides the same length?, so it is a regular polygon.
A polygon must have at least three sides; then it is a triangle. Mathematicians found out, that there are two principles, which apply to all triangles:
The sum of all angles of a triangle is always 180°.
The length of one side changes according to the size of the opposite angle. The largest angle is opposite the longest side. There are basically six types of triangles:
A right triangle has one right angle, i.e. one of 90°. The longest side is opposite this angle.
An isosceles triangle has two sides of equal length. The Shop, opposite these sides, are therefore the same.
An acute triangle has only acute angles; That means, that each angle is less than 90°.
A scalene triangle has three sides of different lengths.
An obtuse triangle has one angle, which is greater than 90°.
An equilateral triangle has three equal sides and three equal angles.