Question

What are the answer

Answer 1

Answer:

1)556.11 cm²

2)164.05 cm²

3)117.70 cm²

Step-by-step explanation:

1) We have a cylinder and a cone on top of it.

Formula for total surface area of cylinder is;

T.S.A = 2πrh + 2πr²

However, the top is not available for calculation here. Thus, we will use;

TSA = 2πrh + πr²

Thus;

TSA = 2π(5 × 12) + π(5)²

TSA = 455.53 cm²

The top is a cone but it's bottom is not included and so we will use lateral surface area of cone = πrL

L is the slanting height and can be calculated from pythagoras theorem ;

L = √(5² + 4²)

L = √41

Thus;

LSA = π × 5 × √41 = 100.58 cm²

Overall surface area = 455.53 + 100.58. Overall surface area = 556.11 cm²

2) for the box down;

TSA = 2lw + 2lh + 2hw

Since the top face is not used, then

TSA = lw + 2lh + 2hw

TSA = (5 × 5) + 2(5 × 5) + 2(5 × 5)

TSA = 125 cm²

For the prism on top, since the bottom is not included, we will use lateral surface are;. LSA = ½Pl

Where P is perimeter of base and L is slant height.

P = 5 × 4 = 20 cm

Radius is 5/2 = 2.5 and so using pythagoras theorem;

L = √(2.5² + 3²)

L = 3.905 cm

Thus;

LSA = ½ × 20 × 3.905 = 39.05 cm²

Overall surface area = 39.05 + 125 = 164.05 cm²

C) for the box down;

TSA = 2lw + 2lh + 2hw

Since the top face is not used, then

TSA = lw + 2lh + 2hw

TSA = (4 × 4) + 2(4 × 4) + 2(4 × 4)

TSA = 80 cm²

For the half cylinder on top;

Surface area ;

T.S.A = 2πrh + 2πr²

Since half cylinder;

TSA = πrh + πr²

TSA = π((2 × 4) + 2²))

TSA = 37.7 cm²

Overall total surface area = 80 + 37.7 ( 117.70 cm²