def add_T_label(self, x_val, **kwargs):
    triangle = RegularPolygon(n=3, start_angle=(np.pi / 2))
    triangle.set_height(MED_SMALL_BUFF)
    triangle.move_to(self.coords_to_point(x_val, 0), UP)
    triangle.set_fill(WHITE, 1)
    triangle.set_stroke(width=0)
    T_label = TexMobject(self.variable_point_label)
    T_label.next_to(triangle, DOWN)
    v_line = self.get_vertical_line_to_graph(x_val, self.v_graph, color=YELLOW)
    self.play(DrawBorderThenFill(triangle), ShowCreation(v_line), Write(T_label, run_time=1), **kwargs)
    self.T_label_group = VGroup(T_label, triangle)
    self.right_v_line = v_line
def add_T_label(self, x_val, **kwargs):
    triangle = RegularPolygon(n=3, start_angle=(np.pi / 2))
    triangle.set_height(MED_SMALL_BUFF)
    triangle.move_to(self.coords_to_point(x_val, 0), UP)
    triangle.set_fill(WHITE, 1)
    triangle.set_stroke(width=0)
    T_label = TexMobject(self.variable_point_label)
    T_label.next_to(triangle, DOWN)
    v_line = self.get_vertical_line_to_graph(x_val, self.v_graph, color=YELLOW)
    self.play(DrawBorderThenFill(triangle), ShowCreation(v_line), Write(T_label, run_time=1), **kwargs)
    self.T_label_group = VGroup(T_label, triangle)
    self.right_v_line = v_line