A pyramid has a parallelogram shaped base and a peak directly above its center. Its base's sides have lengths of 8 8 and 6 6 and the pyramid's height is 9 9. If one of the base's corners has an angle of (5pi)/125π12, what is the pyramid's surface area?

1 Answer
Oct 18, 2017

Total surface area = 168.7614=168.7614

Explanation:

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CH = 6*sin ((5pi)/12) = 5.7956CH=6sin(5π12)=5.7956
Area of parallelogram base = a* b1 = 6* 5.7956=33.7736=ab1=65.7956=33.7736

EF = h_1 = sqrt(h^2 + (a/2)^2) = sqrt(9^2 + 4^2) = sqrt97EF=h1=h2+(a2)2=92+42=97
Area of Delta AEF = BEC = (1/2)*b*h_1 = (1/2)*6*sqrt97=3sqrt97

EG = h_2 = sqrt(h^2+(b/2)^2 = sqrt(9^2 + 3^2 = sqrt90
Area of Delta = CED = AEC = (1/2)*a*h_2 = (1/2)*8*sqrt90=4sqrt90

Lateral surface area = 2* DeltaAED + 2*Delta CED
= 2*3sqrt97 + 2*4sqrt90 = 59.0931 + 75.8947 = 134.9878

Total surface area =Area of parallelogram base + Lateral surface area = 33.7736 + 134.9878 =168.7614