Answer :
Answer:
Q4: A. the second cylinder
Q5: [tex]$\text{Surface Area} =3960 cm^2$[/tex]
Q6: B. Michael
Step-by-step explanation:
Q4:
Cylinders:
- The first is of radius 7 and height 4
- The second is of radius 6 and height 7
[tex]\text{Surface Area} =2\pi r^2+2\pi r h[/tex]
Cylinder 1:
[tex]C_{1}SA =2\pi r^2+2\pi r h[/tex]
[tex]C_{1}SA =2\pi (7)^2+2\pi (7) (4)[/tex]
[tex]C_{1}SA =98\pi +56\pi\\C_{1}SA =154\pi \text{square units}[/tex]
Cylinder 2:
[tex]C_{2}SA =2\pi r^2+2\pi r h[/tex]
[tex]C_{2}SA =2\pi (6)^2+2\pi (6) (7)[/tex]
[tex]C_{2}SA =72\pi +84\pi\\C_{2}SA =156\pi \text{square units}[/tex]
Q5:
Cylinder:
Radius = 21 cm
Height = 9 cm
[tex]$\pi =\frac{22}{7} $[/tex]
[tex]\text{Surface Area} =2\pi r^2+2\pi r h[/tex]
[tex]$\text{Surface Area} =2\frac{22}{7} (21)^2+2\frac{22}{7} (21) (9)$[/tex]
[tex]$\text{Surface Area} =882\frac{22}{7} +378\frac{22}{7} $[/tex]
[tex]$\text{Surface Area} =2772 +1188$[/tex]
[tex]$\text{Surface Area} =3960 cm^2$[/tex]
Q6:
Cylinder of height 28 and radius 9.
[tex]\text{Surface Area} =2\pi r^2+2\pi r h[/tex]
[tex]\text{Surface Area} =2\pi (9)^2+2\pi (9) (28)[/tex]
[tex]\text{Surface Area} =162\pi +504\pi[/tex]
[tex]\text{Surface Area} =666\pi[/tex]
Michael is correct.
Answer:
4. A
5. 3960 cm²
6. B
Step-by-step explanation:
#4. The surface area of a cylinder is denoted by: A = 2πr² + 2πrh, where r is the radius and h is the height. Plug the given values for the two cylinders in:
1st cylinder: A = 2πr² + 2πrh = 2π * 7² + 2π * 7 * 4 = 154π
2nd cylinder: A = 2πr² + 2πrh = 2π * 6² + 2π * 6 * 7 = 156π
So, the second cylinder has the larger surface area: A.
#5. Use the area equation again here: A = 2πr² + 2πrh.
The radius is 21 and the height is 9, so:
A = 2πr² + 2πrh
A = 2 * (22/7) * 21² + 2 * (22/7) * 21 * 9 = 3960 cm²
#6. Use the area equation again here: A = 2πr² + 2πrh.
The radius is 9 and the height is 28, so:
A = 2πr² + 2πrh
A = 2π * 9² + 2π * 9 * 28 = 666π
Thus, Michael is correct: B.