The base of a pyramid is a square of side 8cm. If its vertex is directly above the centre, find the height, given that the edge is 4.3cm
A. 6cm B. 5cm C. 4cm D. 3cm
Correct Answer: C
Explanation
Base of pyramid of a square of side 8cm vertex directly above the centre edge = \(4\sqrt{3}\)cm From the diagram, the diagonal of one base is AC2 = 82 + 82 Ac2 = 64 + 64 = 128 AC = \(8\sqrt{2}\) but OC = \(\frac{1}{2}\)AC = 8\(\sqrt{\frac{2}{2}}\) = \(4\sqrt{2}\)cm OE = h = height h2 = (\(4\sqrt{3}\))2 16 x 2 - 16 x 2 48 - 32 = 16 h = \(\sqrt{16}\) = 4