(c) $\because v(t) = \cos{\pi t},$ $\Rightarrow \frac{ds}{dt} = \cos{\pi t}$ $\Rightarrow s = \frac{\sin{\pi t}}{\pi} + c,\ at\ t = 0,\ s = 4,\ c = 4$ $\Rightarrow s = \frac{\sin{\pi t}}{\pi} + 4$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.