This is LaTeX code:
[latex]
+ \int_{ - 1}^1 {\left( {P\left( {x, - \sqrt {1 - x^2 } } \right),Q\left( {x, - \sqrt {1 - x^2 } } \right)} \right)\left( {1,\frac{x} {{\sqrt {1 - x^2 } }}} \right)dx}
[/latex]