[填空题]
A right pyramid has apex V and square sce(cp( mu jf;p7vn8t rdl3+1base ABCD with the base diagonal AC=4cm) 1o dm9+.v rei5xsf aedwe:0h. The sloping edges ares1f:ia59wrx0vee+ dm.)deho 7 cm long.
1.Calculate the size of the angle that sloping edge VC makes with
the pyramid base. ${\circ}$
2.Calculate the vertical height of the pyramid, VO. cm
3.Calculate the volume of the pyramid. $cm^3$