Please explain the following please more simply:

2 lim sin e = 1 3-0 We now use a geometric argument to prove Equation 2. Assume first that 0 lies between 0 and #7/2. Figure 2(a) shows a sector of a circle with center O, central angle 0, and radius 1. BC is drawn perpendicular to OA. By the definition of radian measure, we have arc AB = 0. Also, | BC| = | OB | sin 0 = sin 0. From the diagram we see that E | BC|