2. The bottom of a cuboid is square, with an area of 900 square centimeters. Its side area is 7200 square centimeters. The volume of this cuboid is (2 16000) cubic centimeters.
3. If the height of a cuboid increases by 5cm, it will become a cube, and the surface area will increase by 180cm. Find the surface area of the original cuboid.
According to the problem, the bottom of the original cuboid is square, and the part with increased surface area after increasing the height by 5 cm is the lateral area with four sides, so
1 The increased area of the lateral area is 180÷4=45 (square centimeter).
The side length of the bottom square is 45÷5=9 (cm).
The original height of a cuboid is 9-5=4 (cm).
The side area of the original cuboid is 2x(9x9)+4x(9x4)=306 (square centimeter).
The sum of the sides of a cuboid is 88 cm. It is 9 cm long and 6 cm wide. Cut it into three cuboids (vertical). How many square centimeters does the surface area increase?
According to the conditions in the question, the height of the cube is 88÷4-9-6=22-9-6=7 (cm).
Cut vertically into three cuboids, and the increased area is four horizontal areas, with a width of 6 cm and a height of 7 cm, which is 4x(6x7)=4x42= 168 (square cm).