Page 160 - NUMINO TG_6A

10Fill It with Chocolate Pieces Unit

2 . Find the surface area of the cylinder. 2 in. 2. Have students find the surface area of
10 in. each cylinder. Explain to them that the
a. b. surface area of any solid object is the sum of
the area of all its sides. Therefore, for
5cm cylinders, the surface area equals the sum of
the area of the base plus the area of the top
7cm plus the area of the curved surface that
makes up the body of the cylinder. Remind
(5 5 3.14) 2 (2 2 3.14) 2 students that the radius is equal to half the
+(5 2 3.14 7) 376.8 (cm2) +(2 2 3.14 10) 150.72 (in.2) diameter.

c . 6 ft d. 20 m

10 ft 6m

(3 3 3.14) 2 (10 10 3.14) 2 3. Have students work together to find the
+(3 2 3.14 10) 244.92 (ft2) +(10 2 3.14 6) 1,004.8 (m2) surface area of the figure.

Have students write down and explain their

answers to both problems.

3 . Find the surface area of the figure. Refer to .

Have students work together to find the surface area of the figure below. They must Team
find the area of the lateral surface of the larger cylinder, the area of the lateral surface Project
of the smaller cylinder, and the area of the larger circle subtracted by the area of the
smaller circle.

4cm Don t forget the

surface in the middle.

8cm (4 4 3.14 2 2 3.14) 2 8)
+(4 2 3.14 8) + (2 2 3.14

376.8 (cm2)

2cm

10. Fill It with Chocolate Pieces 87

Remind students to look carefully at the values next to the figures. In 2a and 2b, the radius is given. In 2c and
2d, the diameter is given. The diameter is twice the radius. Therefore, the formula for 2c and 2d becomes: (r

r ) 2 (d h) area.
To solve question 3, students must find the area of the lateral surface of the greater cylinder, the area of the
lateral surface of the smaller cylinder, and the area of the greater circle subtracted by the area of the smaller
circle.

6A Unit 10 143