The motion of a human body through space can be modeled as the motion of a particle at the body's center of mass as we will study in a later chapter. The components of the displacement of an athlete's center of mass from the beginning to the end of a certain jump are described by the equations

xf = 0 + (10.5 m/s)(cos 18.5°)t
0.230 m = 0.790 m + (10.5 m/s)(sin 18.5°)t - ½(9.80 m/s²)t²

where t is in seconds and is the time at which the athlete ends the jump.

Identify the athlete's position at the takeoff point.
(i + j) m