According to the meaning of right angle, we can know that to know whether an angle is right angle, we can compare it with the right angle on a triangle; That is, the largest angle on a triangle. Definition in Geometry Elements: When the adjacent angles formed by a straight line and another horizontal line are equal, each of these angles is called a right angle, and this straight line is called perpendicular to another straight line.

Angle is a geometric noun, and the definition of angle is that a figure composed of two rays with a common endpoint is called angle. This common endpoint is called the vertex of the angle, and these two rays are called the two sides of the angle. The general angle is assumed to be in Euclidean plane, but it can also be defined in non-Euclidean geometry.

Angle is widely used in geometry and trigonometry. Angles can be divided into acute angle, right angle, obtuse angle, right angle, rounded corner, negative angle, positive angle, upper angle, lower angle and 0 angle, which are 10 respectively. An angle measuring system with degrees, minutes and seconds as the unit is called an angle system, and the symbol of the angle is mathematically represented by ∠.