1. In the same circle or the same circle, if the distance between two central angles, two peripheral angles, two groups of arcs and one center of two chords is equal, the corresponding other groups are equal.

2. In the same circle or equal circle, the circumferential angle of an equal arc is equal to half of the central angle it faces (the circumferential angle and the central angle are on the same side of the chord).

Extended data

A line segment connecting any two points on a circle is called a chord, and the longest chord in the same circle is a diameter. The angle of the vertex on the center of the circle is called the central angle. The part between any two points on a circle is called an arc, which is represented by "⌒".

Relevant calculation formula: (R is the radius of the sector, N is the degree of the central angle of the arc, π is the pi, and L is the arc length corresponding to the sector).

Sector arc length L= central angle (radian system) ×R= nπR/ 180(θ is central angle) (r is sector radius).

Sector area S=nπ R? /360=LR/2(L is the arc length of the sector)

Radius of cone bottom surface r=nR/360(r is the radius of bottom surface) (N is the central angle)

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