# The polar form of the complex number $(i^{25})^{3}$ is
$\begin{array}{1 1}(1)\cos\frac{\pi}{2}+i\sin\frac{\pi}{2}&(2)\cos\pi+i\sin\pi\\(3)\cos\pi-i\sin\pi&(4)\cos\frac{\pi}{2}-i\sin\frac{\pi}{2}\end{array}$