Question 7: According to the topic, the radius of the upper and lower bottom surfaces of the cylinder is 9cm. According to the circumference of the circle C=2πR, the area S=πR? The formula can be obtained as follows:

The circumference of a circle c = 2 * 3.14 * 9 = 56.52; Area S=3. 14*9*9=254.34.

Therefore, the required pattern area is s1= 56.52 * 80 = 4521.6cm2..

The required area of yellow cloth is S2 = 254.34 * 2 = 508.69cm2

8 If the question is like this, can you calculate the upper and lower areas of lanterns as S 1=2*πR? = 2 * 3. 14 * 10 * 10 = 628 cm2

The transverse area is S2 = c * h = 2 * 3.14 *10 * 30 =1884cm2.

So the color paper needed to make a cylindrical lantern is S = 628+1884-78.5 * 2 = 2355cm2.

Question 9: The iron sheet needed for bucket is S = 3.14 *12 * 3/4 *12 * 3.14 *12 * 3/4.

10, the height of the cylinder is h =188.4/(2 * 2 * 3.14) =15dm.

1 1 Question: The surface area of wood is increased by S = 6 * 3.14 * 0.3 * 0.3 =1.6956m2.