Answer:
243cm^3
Step-by-step explanation:
By Pythagoras' Theorem,
height of the prism ^2 + 5.4^2 = 7.8^2
height of the prism = ±√(7.8^2 -5.4^2) = ±5.6285cm (5s.f.) (rej. - 5.6285 since height > 0cm)
volume of the prism = 1/2 x 5.4 x 5.6285 x 16 = 243cm^3 (3s.f.)
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