The pile of balls (2)

The pile is made up of tennis balls with diameter 6.5cm. You have to calculate H, the height of this pile.
Each point is in the centre of each ball. What type of figure is ABC? rigth triangle
isoscel triangle
equilateral triangle
AB = cm
What type of figure is ABCS? a rhombus
a cuboid
a right prism
a pyramid
AS = cm