It is 6CM high, and a 4CM high trademark should be attached outside the box. How many square centimeters of trademark paper does a can need? How much iron does it take to make a can?
4 * 2 * 3.14 * 6 =150.72cm2 (trademark area)
4 * 4 * 3.14 * 2 =100.48 cm2
100.48+150.72 = 251.2cm2 (iron sheet area)
2. A cylindrical wooden stick with a length of 12DM and a cross-sectional diameter of 4CM is cut into three sections on average, and then all of them are colored. What is the area of the colored part?
4 * 3.14 *12 =150.72 square decimeter
4/2=2 decimeters
2*2*3. 14*6=75.36 square decimeter.
150.72+75.36=226.08 square decimeter.