Mathematics: For brainiest:):):):):):):):)

For brainiest:):):):):):):):) - id12589887, Saberabuomar2007

Ответ:

hermesrobles

31.12.2020

Step-by-step explanation:

We can find the surface area of the dumbbell by adding the surface areas of each part. We have two equal round ends of the dumbbell to count and the skinnier inside. Each is a cylinder and each can be found by finding the area of the base (times 2 for two bases) and adding it to the circumference times the height.

$2(\pi r^{2} )+(\pi d)h$

Dumbbell Ends

There are two ends and so we will count this measurement twice. The diameter is 12.5. The radius is half of this and is 6.25. The height is 8.

$2(\pi r^{2} )+(\pi d)h$

$2(\pi (6.25)^{2} )+(\pi 12.5)8$

$2(\pi 39.0625 )+(\pi 100$

245.4369+314= 559.43

But we must count is twice, so 559.43(2)=1118.87 cm squared.

Dumbbell Middle

The diameter is 2.50. Radius is 1.25. The height is 10.5. The ends actually don't show because they are attached. So we will only calculate the second part and add it to the other.

$(\pi 2.5)10.5$ =82.47

82.47+1118.87=1201.33 cm squared.

Why is this too large? Why isn't it an answer choice? Because the ends of the middle don't show, they also take up that much area on other side. They are not part of the surface area and they make it smaller. So we will subtract that area now.

$2(\pi 1.25^{2} )$ =9.817

1201.33-9.817=1191.84 cm squared.

0,0(0 оценок)

For brainiest:):):):):):):):)

Ответ:

Ответ:

Ask your question to the AI advisor

More tips

Answers on questions: Mathematics

Ask an AI advisor a question