Repository: ManimCommunity/manim
File: manim/mobject/geometry.py (Python)

Code before:
                    ArcAngle(line1, line2, radius=0.5, quadrant=(-1,1), stroke_width=8, other_angle=True),
                    ArcAngle(line1, line2, radius=0.7, quadrant=(-1,-1), color=RED),
                    ArcAngle(line1, line2, other_angle=True),
                    ArcAngle(line1, line2, radius=0.4, quadrant=(1,-1)),
                    ArcAngle(line1, line2, radius=0.5, quadrant=(-1,1), stroke_width=8),
                    ArcAngle(line1, line2, radius=0.7, quadrant=(-1,-1), color=RED, other_angle=True),
                ]
                line_list = VGroup( *[VGroup() for k in range(8)] )
                for k in range(8):
                    linea = line1.copy()
                    lineb = line2.copy()
                    line_list[k].add( linea )
                    line_list[k].add( lineb )
                    line_list[k].add( arcangles[k] )
                line_list.arrange_in_grid(n_rows=2, n_cols=4, buff=1.5)
                self.add(
                    line_list
                )

    """

    def __init__(
        self,
        line1,
        line2,
        radius=0.3,
        quadrant=(1, 1),
        other_angle=False,
        dot=False,
        dot_radius=None,
        dot_distance=0.55,
        dot_color=WHITE,
        **kwargs
    ):
        self.radius = radius
        self.quadrant = quadrant
        self.dot_distance = dot_distance
        inter = line_intersection(
            [line1.get_start(), line1.get_end()], [line2.get_start(), line2.get_end()]
        )
        anchor_angle_1 = inter + quadrant[0] * radius * line1.get_unit_vector()
        anchor_angle_2 = inter + quadrant[1] * radius * line2.get_unit_vector()

        angle_1 = angle_of_vector(anchor_angle_1 - inter)
        angle_2 = angle_of_vector(anchor_angle_2 - inter)

        if other_angle == False:
            start_angle = angle_1
            if angle_2 > angle_1:
                angle_fin = angle_2 - angle_1
            else:

Review comment (suggestion):
```suggestion
        radius=None,
```
I'd prefer this default to be `None` and calculated dynamically based on the size of the shorter of the two segments from the intersection. See this example:
```py
class Test(Scene):
    def construct(self):
        l1 = Line(ORIGIN, RIGHT)
        l2 = Line(ORIGIN, UP*.2)
        a = ArcAngle(l1, l2)
        self.add(l1,l2,a)
```
![image](https://user-images.githubusercontent.com/29168469/110840115-32bed700-8259-11eb-9c5c-d7e040b19911.png)


Code after:
                angles = [
                    Angle(line1, line2),
                    Angle(line1, line2, radius=0.4, quadrant=(1,-1), other_angle=True),
                    Angle(line1, line2, radius=0.5, quadrant=(-1,1), stroke_width=8, other_angle=True),
                    Angle(line1, line2, radius=0.7, quadrant=(-1,-1), color=RED),
                    Angle(line1, line2, other_angle=True),
                    Angle(line1, line2, radius=0.4, quadrant=(1,-1)),
                    Angle(line1, line2, radius=0.5, quadrant=(-1,1), stroke_width=8),
                    Angle(line1, line2, radius=0.7, quadrant=(-1,-1), color=RED, other_angle=True),
                ]
                line_list = VGroup( *[VGroup() for k in range(8)] )
                for k in range(8):
                    linea = line1.copy()
                    lineb = line2.copy()
                    line_list[k].add( linea )
                    line_list[k].add( lineb )
                    line_list[k].add( angles[k] )
                line_list.arrange_in_grid(n_rows=2, n_cols=4, buff=1.5)
                self.add(
                    line_list
                )

    """

    def __init__(
        self,
        line1,
        line2,
        radius=None,
        quadrant=(1, 1),
        other_angle=False,
        dot=False,
        dot_radius=None,
        dot_distance=0.55,
        dot_color=WHITE,
        elbow=False,
        **kwargs
    ):
        self.quadrant = quadrant
        self.dot_distance = dot_distance
        self.elbow = elbow
        inter = line_intersection(
            [line1.get_start(), line1.get_end()], [line2.get_start(), line2.get_end()]
        )

        if radius is None:
            if quadrant[0] == 1:
                dist_1 = np.linalg.norm(line1.get_end() - inter)
            else:
                dist_1 = np.linalg.norm(line1.get_start() - inter)
            if quadrant[1] == 1: