Arc length formulas: n is the center perspective number, r is radius, α is the center Angle radian. l=nπr÷180 or l=n/180·πr or l=|α|r

In radius is R circle, because Arc length of 360° central Angle is tantamount to Circumference C=2πR, so Arc length of n° central Angle is l=n°πR÷180°.

In radian system, if the center Angle of the arc is θ, then there is formulas L=Rθ. sector area formulas S=LR/2, corresponding to the sector area Calculator formulas S=RRθ/2.

In a circle, a line segment arbitrarily connecting the center of the circle to a point on the circle is called a circle radius. This is usually denoted by letter r.

Center Angle The vertex on the center of the circle, the Angle on both sides of the Angle and the circle are called the center Angle. The value range of the central Angle ∠AOB is 0°< < AOB < 360°