$\Large %n$

$\Large %n$

$\huge r$

演示

r = 0.5 (slider from 0.5 to 3)
O = (0, 0)
k = 1 (slider from 0 to 1, step 0.001)
B: (-0.5, 0)
c = Circle(O, r)
A = Point(c, k)
f = Segment(O, A)
d = If(k > 0, CircleArc[O, B, A])
text1 = If(k ≟ 1, Text["圆", O + (0.5, 0.5)])
C: (x(A) + 0.4, y(A) - 0.1)

Tool: 简易坐标系
请选择原点，分别输入：x最小、最大值，y最小、最大值
Input: A, a, b, c, d
Output: B, C, O, u, v

$\huge\textcolor{}{x}$

$\huge\textcolor{}{y}$

$\Large\textcolor{}{O}$

A: (0, 0)
u = Vector(A + (a - 1, 0), A + (b + 1, 0))
v = Vector(A + (0, c - 1), A + (0, d + 1))
B: A + (b + 1, 0)
C: A + (0, d + 1)
O: A