In the ellipse, the distance between its foci is $$6$$ and minor axis is $$8$$. Then its eccentricity is :

A triangular park is enclosed on two sides by a fence and on the third side by a straight river bank. The two sides having fence are of same length $$x$$. The maximum area enclosed by the park is

The function $$f\left( x \right) = {x \over 2} + {2 \over x}$$ has a local minimum at

Let $$A = \left( {\matrix{ 1 & 2 \cr 3 & 4 \cr } } \right)$$ and $$B = \left( {\matrix{ a & 0 \cr 0 & b \cr } } \right),a,b \in N.$$ Then