caption: The image shows a diagram of a triangle with a point at the end of it and a line going through it. The text written on the paper reads "Figure 1.1.1 of the Equation of a Triangle". The diagram is composed of a series of points connected by a line, with the x-axis and y-axis labeled. The point at each point is labeled with the corresponding equation, and the line connecting the points is marked with a dotted line. The diagram also includes a legend at the bottom, which explains the meaning of the equation.