Answer
$=100\arcsin(\frac{x}{10})+C$
Work Step by Step
$\int\frac{100}{\sqrt {100-x^{2}}}dx$
Use $\int\frac{1}{\sqrt{(a)^{2}-(u)^{2}}}du=\arcsin(\frac{u}{a})+C$
$\int \frac{100}{\sqrt {100-x^{2}}}dx = \int\frac{100}{\sqrt{(10)^{2}-(x)^{2}}}dx$.
$=100\arcsin(\frac{x}{10})+C$