Question

PLS MATHS EXPERT PLS ANSWER ASAP I AM GIVING OUT ALL MY POINTS!!!!!

Answer 1

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.

Answer 2

Answer:

Q4: A. the second cylinder

Q5: $\text{Surface Area} =3960 cm^2$

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

$\text{Surface Area} =2\pi r^2+2\pi r h$

Cylinder 1:

$C_{1}SA =2\pi r^2+2\pi r h$

$C_{1}SA =2\pi (7)^2+2\pi (7) (4)$

$C_{1}SA =98\pi +56\pi\\C_{1}SA =154\pi \text{square units}$

Cylinder 2:

$C_{2}SA =2\pi r^2+2\pi r h$

$C_{2}SA =2\pi (6)^2+2\pi (6) (7)$

$C_{2}SA =72\pi +84\pi\\C_{2}SA =156\pi \text{square units}$

Q5:

Cylinder:

Radius = 21 cm

Height = 9 cm

$\pi =\frac{22}{7}$

$\text{Surface Area} =2\pi r^2+2\pi r h$

$\text{Surface Area} =2\frac{22}{7} (21)^2+2\frac{22}{7} (21) (9)$

$\text{Surface Area} =882\frac{22}{7} +378\frac{22}{7}$

$\text{Surface Area} =2772 +1188$

$\text{Surface Area} =3960 cm^2$

Q6:

Cylinder of height 28 and radius 9.

$\text{Surface Area} =2\pi r^2+2\pi r h$

$\text{Surface Area} =2\pi (9)^2+2\pi (9) (28)$

$\text{Surface Area} =162\pi +504\pi$

$\text{Surface Area} =666\pi$

Michael is correct.