扇形的弧長與面積
Author: 藍邦偉　老師

扇形的面積與弧長

r = 7 (slider from 1 to 7, step 1)
C: x^(2.0) + y^(2.0) = r^(2.0)
O = (0, 0)
A = Point(C)
θ = 2.076941809873252 rad (slider from 0 to 6.283185307179586, step 0.017453292519943295)
B = Rotate(A, θ, O)
s = CircleSector(O, A, B)
a = Segment(O, A)
α = Angle(A, O, B)
Area = Area(s)
文字3: "面積=  \frac{ 1 }{2 }r²θ=  " + " \frac{ 1 }{2 } " + (r^(2.0)) + " \times{  }" + (θ / 3.141592653589793) + "=" + s
c = CircleArc(O, A, B)
文字4: "扇形的弧長與面積皆為圓的 \frac{ " + θ + " }{ 360}=" + (θ / 360.0)
文字2: "弧長s=rθ=" + r + "\times{  } " + (θ / 3.142) + "=" + c