We are asked to evaluate the integral:
\[
I = \int \frac{\sin^1 x}{\sqrt{1 - x^2}} \, dx
\]
1. Step 1: Recognize the form of the integrand
The given integral is closely related to the standard integral form:
\[
\int \frac{\sin x}{\sqrt{1 - x^2}} \, dx
\]
This is a standard trigonometric integral. We know from calculus that:
\[
\int \frac{\sin x}{\sqrt{1 - x^2}} \, dx = \frac{\sin^2 x}{2}
\]
2. Step 2: Apply the formula
Using the known formula, the result of the integral is:
\[
\frac{\sin^2 x}{2}
\]
Thus, the answer is:
\[
I = \frac{\sin^2 x}{2}
\]