6. A three hinged arch shown in the below figur is quarter of a circle, If the vertical and horizontal components of reaction at A are equal, the value of ? is
9. If a single pipe of length L and diameter D is to be replaced by three pipes of same material, same length and equal diameter d (d < D), to convey the same total discharge under the same head loss, then d and D are related by
10. The Piezometric head at point C, in the experimental set-up shown in the below figure when the flow takes place under a constant head through the soils A and B is