Its side development diagram is a square with a side length of 10 cm.
The height is 10 cm, and the perimeter of the bottom surface is 10 cm.
The length and width of a cuboid are
10÷4 = 2.5 cm.
The surface area of this cuboid is
(2.5×2.5+2.5× 10+2.5× 10)×2 = 1 12.5 cm2。
2. A cube with a side length of 6 cm is cut in half on average, and what is the surface area?
The original surface area of the cube should be 6*6*6=2 16 cubic centimeter.
The surface area of the new semi-cube is 3*6*4+6*6*2= 144 cubic centimeter.
The sum of the surface areas of the two new cubes is 6*6*6+6*6*2=288 cubic centimeters.
It can also be 144*2=288 cubic centimeters.
3. Matchbox. It is 4.5 centimeters long. 3.5 cm wide and 1.8 cm high. If you take the length and width of the inner box. Height is calculated by the length, width and height of the coat. What is the area of cardboard used in the inner box and the outer box? Sticky places don't count.
5 sides of the inner box (less than 1 side) need hard paper.
4.5×3.5+4.5× 1.8×2+3.5× 1.8×2
= 15.75+ 16.2+ 12.6
= 44.55 (square centimeter)
4 sides (less than 2 sides) of the outer box need hard paper.
4.5×3.5×2+4.5× 1.8×2
=3 1.5+ 16.2
= 47.7 square centimeters