A periodic function $\large{f(t)},$ with a period of 2$\pi$, is represented as its fourier series,
$\large{f(t)} = a_0 + \sum_{n=1}^{\infty }a_n cos nt + \sum_{n=1}^{\infty} b_n sin nt.$}$If$\large{f(t)} = \left\{\begin{matrix} Asint, & 0 \le t\le \pi\\ 0, & \pi < t < 2\pi \end{matrix}\right.$the fourier series coefficients a_1 and b_1 of$\large{f(t)} $are 1.$a_1 = \frac{A}{\pi}; b_1 = 0$2.$a_1 = \frac{A}{2}; b_1 = 0$3.$a_1 = 0;b_1 = \frac{A}{\pi}$4.$a_1 = 0;b_1 = \frac{A}{2}\$