Question

DUPLICATE. WITH ATTACHMENTS
Find the surface area of the pyramid shown to the nearest whole number.
7.
72 ft2
128 ft2
56 ft2
22 ft2

8.
1,300 m2
390 m2
650 m2
628 m2

9. Find the slant height x of the pyramid shown, to the nearest tenth.
4.35 mm
9.2 mm
6.9 mm
3.6 mm

10. Find the surface area of the cone to the nearest tenth.
132 cm2
138 cm2
490.1 cm2
867.1 cm2

11. Find the slant height of the cone to the nearest whole number.
20 m
22 m
21 m
19 m
"

Answer 1

7.) Area of a square pyramid is given by A = s^2 + 2sl; where s is the side length of the base and l is the slant height.
Area of given pyramid = 4^2 + (2 x 4 x 7) = 16 + 56 = 72 ft^2

8.) Area of the given pyramid is the area of the hexagonal base plus the area of the six slant triangles.
Area of hexagonal base = (3sqrt(3))/2 x 10^2 = 150 x 1.732 = 259.8
Area of the 6 traingles = 6(1/2 x 10 x 13) = 6 x 65 = 390
Total surface area of the pyramid = 259.8 + 390 = 649.8 ≈ 650 m^2

9.) Using pythagoras rule, the slant height is sqrt(6^2 + 3.5^2) = sqrt(36 + 12.25) = sqrt(48.25) = 6.9 mm

10.) The surface area of a cone is given by πr^2 + πrl
Area = π x 6^2 + π x 6 x 20 = 36π + 120π = 490.1 cm^2

11.) l = sqrt(r^2 + h^2) = sqrt(11^2 + 16^2) = sqrt(121 + 256) = sqrt(377) = 19m