[填空题]
A right pyramid has apex V and square ba+yildo,ot n.4 se ABCD with the base di(;li +ndaw 1rzr0zlb( agonal AC=4cm. The sloping edges are 7 az10lrl(+iwd( brnz ;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. $cm^3$