Triangle angles

A corner is a geometric figure formed by two rays (sides of an angle) coming from one point (which is called the vertex of the angle). A plane containing both sides of an angle is divided by an angle into two areas. Each of these areas, combined with the sides of the corner, is called a flat angle (or simply an angle, if this does not cause discrepancies). One of the flat corners (usually the smaller of the two) is sometimes conventionally called internal, and the other external. Points of a flat angle that do not belong to its sides form the inner region of the flat angle.

Triangle — is a geometric figure that has three points that do not lie on the same line and three segments that pair these points in pairs. The points of a triangle are usually called its vertices, and the segments are called its sides.

In total, the angles of the triangle give 180 °, so knowing two of them, we can calculate the third: α = 180° - β - γ. Through the cosine theorem, the angle of the triangle can be found, knowing all three sides of the triangle, as shown in above formulas.