Question

The shaded area in the diagram below shows the cross section of a square pyramid intersected by a plane parallel to the base. The pyramids edges are all 20 cm long. What is the perimeter of the shaded area?

39 cm

52 cm

21 cm

49 cm

Answer 1

any ideas?

Answer 2

i cant tell what the 7 and the 13 are labeling

Answer 3

that's the edge going upward

Answer 4

13 is the edge of the upper pyramid

Answer 5

7 is the remaining bit between the upper and larger pyramid

Answer 6

ok, and the 7 is the edge for the lower part

Answer 7

alright

Answer 8

yes

Answer 9

so, how would i find one of the sides of the shaded part?

Answer 10

it says that each side is 20 (this is the larger pyramid), agreed?

Answer 11

yes

Answer 12

the smaller pyramid is a similar solid because the base is parallel to the larger base (and it sits inside the larger pyramid)

Answer 13

this means that each side (20) is divided by some number to get 13

Answer 14

ok, now i see what your saying

Answer 15

so the perimeter is?

Answer 16

1.5

Answer 17

1.5(4)=6

Answer 18

no

Answer 19

but 20/1.5=13

Answer 20

yes, you're dividing each number by 1.5 (roughly) to get 13 (roughly)

Answer 21

so each edge in the smaller pyramid will be 13

Answer 22

so the perimeter of each side of the shaded area is 13. Therefore 13(4)=52

Answer 23

each edge is 13

so the perimeter is 52

Answer 24

alright, thanks for the explantion

Answer 25

yw