MCQ
$\mathop {Lim}\limits_{n\, \to \infty } \,\,\frac{\pi }{{6n}}\left[ {{{\sec }^2}\left( {\frac{\pi }{{6n}}} \right) + {{\sec }^2}\left( {2\,\cdot\,\frac{\pi }{{6n}}} \right) + ..... + {{\sec }^2}(n - 1)\frac{\pi }{{6n}} + \frac{4}{3}} \right]$ has the value equal to
- ✓$\frac{{\sqrt 3 }}{3}$
- B$\sqrt 3 $
- C$2$
- D$\frac{2}{{\sqrt 3 }}$