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Please can you look at my solutions and see where I am going wrong? Surface area of pyramids. (1 Viewer)

kpad5991

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SA bottom = 24 x 16 = 384 cm^2

SA front + back = 1/2 (16 x 29.7) x 2 Used Pythagoras h^2 = 32^2 - 12^2, therefore h = 29.7
= 475.2 cm ^2

SA RHS + LHS = 1/2 (24 x 31) x 2 Used Pythagoras (twice) Slant height of front triangle = (root 880)^2 - 12^2 = root 1024, then h^2 = (root 1024)^2 - 8^2 = 31
= 744 cm^2

Total SA = 1603.2 cm^2

The answer is 1592cm^2 ? What mistake am I making? Is it just rounding?
 

may22

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SA front + back = 1/2 (16 x 29.7) x 2 Used Pythagoras h^2 = 32^2 - 12^2, therefore h = 29.7
= 475.2 cm ^2
I think you may have used the wrong numbers for Pythagoras here. It would be 32^2 - 8^2 = h^2
Because the original base length is 16, and when you split the triangle to use Pythagoras, it becomes 8



check through your working again, you might have made similar errors throughout
 

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