When two lines intersect, they create four angles. These angles can be divided into two pairs of vertical angles. Vertical angles are opposite each other and are always equal in measure.
Let’s denote the four angles created by the intersection of the two lines as angle A, angle B, angle C, and angle D. Since angle A and angle B are adjacent and form a straight line, the sum of angles A and B is 180 degrees. Similarly, angles C and D are adjacent and also sum to 180 degrees.
So, if we add all four angles together, we get:
Angle A + Angle B + Angle C + Angle D = 180° + 180° = 360°
Therefore, the sum of all four angles formed when two lines intersect is 360 degrees.