Comprehension Passage
For the next two (2) items that follow:
The integral \(\smallint \frac{{{\rm{dx}}}}{{{\rm{acosx}} + {\rm{b}}\sin {\rm{x}}}}\) is of the form \(\frac{1}{{\rm{r}}}\ln \left[ {\tan \left( {\frac{{{\rm{x}} + {\rm{a}}}}{2}} \right)} \right]\)What is r equal to?
1
a2 + b2
2
\(\sqrt {{{\rm{a}}^2} + {{\rm{b}}^2}} \)
3
a + b
4
\(\sqrt {{{\rm{a}}^2} - {{\rm{b}}^2}} \)