[填空题]
A right pyramid has apex V and squa.q6w :ihkz.h)siz6 y lre base ABCD w2g,bl9r6aqv l ith the base diagonal AC=4cm. The sloping edgell 2a 9r,6gqbvs are 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. $cm^3$