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A right triangular pyramid XYZB is cut from cube as shown in figure. The side of cube is 16 cm. X, Y and Z are mid points of the edges of the cube. What is the total surface area (in cm2) of the pyramid?
A right triangular pyramid XYZB is cut from cube as shown in figure. The side of cube is 16 cm. X, Y and Z are mid points of the edges of the cube. What is the total surface area (in cm2) of the pyramid?
Answer & Solution
Correct Answer:
Option
D
BX = BY = 8 cm
∴ XY = YZ = XZ = 8√2

$$l$$2 = 82 - (4√2)2
$$l$$2 = 32
$$l$$ = 4√2
Total surface area = $$\frac{1}{2}$$ × Perimeter of base × $$l$$ + Area of base
= $$\frac{1}{2} \times 3 \times 8\sqrt 2 \times 4\sqrt 2 + \frac{{\sqrt 3 }}{4}{\left( {8\sqrt 2 } \right)^2}$$
= 96 + 32√3
= 32(3 + √3) cm2
∴ XY = YZ = XZ = 8√2

$$l$$2 = 82 - (4√2)2
$$l$$2 = 32
$$l$$ = 4√2
Total surface area = $$\frac{1}{2}$$ × Perimeter of base × $$l$$ + Area of base
= $$\frac{1}{2} \times 3 \times 8\sqrt 2 \times 4\sqrt 2 + \frac{{\sqrt 3 }}{4}{\left( {8\sqrt 2 } \right)^2}$$
= 96 + 32√3
= 32(3 + √3) cm2
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