. Graph the function fsxd − sinsyxd of Example 5 in the viewing rectangle f21, 1g by f21, 1g. Then zoom in toward the origin several times. Comment on the behavior of this function. In the theory of relativity, the mass of a particle with velocity v is m − m0 s1 2 v 2 yc 2 where m0 is the mass of the particle at rest and c is the speed of light. What happens as v l c2?