Let ABCD be a isosceles trapezoid such that AB∣∣CD and all of its sides are tangent to a circle. [AD] touches this circle at N. NC and NB meet the circle again at K and L, respectively. What is ∣BL∣∣BN∣+∣CK∣∣CN∣?<spanclass=′latex−bold′>(A)</span> 4<spanclass=′latex−bold′>(B)</span> 6<spanclass=′latex−bold′>(C)</span> 8<spanclass=′latex−bold′>(D)</span> 9<spanclass=′latex−bold′>(E)</span> 10 geometrytrapezoidtrigonometrypower of a point