The edge of a cube is 2a cm. Find its surface?
Correct answer: D. 24a2 cm2
- A. 6a2 cm2
- B. 8a2 cm2
- C. 12a2 cm2
- D. 24a2 cm2
Explanation
A cube has surface area 6a^2 when its edge is a. With edge 2a cm, the surface area is 6(2a cm)^2 = 6 x 4a^2 cm2 = 24a^2 cm2. The likely mistake is choosing 6a^2 cm2 by forgetting to square the factor 2.
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Area measures the surface enclosed by two-dimensional figures, while volume measures the space occupied by three-dimensional solids. Problems use formulas for rectangles, triangles, circles, prisms, cylinders, cones, spheres, and composite figures, including unit conversion and the distinction between surface area, lateral area, and volume.
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