Question Video: Identifying the Definition of an Angle Mathematics • First Year of Preparatory School

Video Transcript

Which of the following is the definition of an angle? Option (A) it is the rotation of a point from one position to another around a line segment. Option (B) it is the rotation of a ray from one position to another around the starting point. Option (C) it is a measure of the distance between two points. Option (D) it is a quantity that measures how many points two lines intersect at. Or is it option (E) it is the rotation of a line segment from one position to another around a ray?

In this question, we are asked to identify which of five given options is the correct definition of an angle. We can do this by recalling that an angle is the rotation needed to rotate one ray onto another ray that share the same initial point. We call the shared initial point the vertex of the angle. In particular, we call the rotation needed to rotate one ray onto the other the angle at the vertex. We can see that this matches option (B).

We can also note that we only define rotations in the plane around a point, so options (A) and (E) cannot be correct. Similarly, option (C) is the length of a line segment from its endpoints.