Question

Mr. Rasmussen laid 9 bricks in a row to make a walking path through his garden. If each brick has a length of 8 inches, a width of 3 point five inches, and a height of 3 inches, what is the surface area of the walkway?

9 bricks are shown laying side-by-side to form a line. The dimensions of each brick are shown

eighty-four square inches

six hundred seventy-seven square inches

seven hundred forty-one square inches

seven hundred fifty-six square inches

Answer 1

@CGGURUMANJUNATH

Answer 2

C.

Answer 3

also could u help with this @CGGURUMANJUNATH AND @AnswerMyQuestions

Answer 4

What is the approximate surface area of this pencil? (Use 3 point one four for pi. Round your answer to the nearest whole number.)

A pencil that comes to a point at the end is shown. The part of the pencil that does not come to a point is fifteen centimeters long. The diameter is zero point six centimeters. The top of the pencil, which comes to a point, has a slant height of 2 centimeters.

twenty-eight square centimeters

41 cm2

30 cm2

seventy square centimeters

Answer 5

I am assuming that the pencil is round?

Answer 6

yes @richyw

Answer 7

@AnswerMyQuestions and @dragonknight326 : I remind you that the OpenStudy Code of Conduct forbids you from asking others to do your work for you and/or to Answer Your Questions, and it also forbids other users from doing others' work for them and providing answers. Read the Code of Conduct. Further offenses will lead to your suspension.

Answer 8

See:

http://openstudy.com/code-of-conduct

Answer 9

thats strange @mathmale i dont remember saying this is homeowrk

Answer 10

so I just made a quick sketch of the situation. do you know the formula for the surface area of a circular cone in terms of its slant height?

Answer 11

@dragonknight326 : I advise you to follow the Code of Conduct if you want to continue benefiting from OpenStudy. Doesn't matter what you label your work: homework or not, you are not to ask for or expect others to do your work. If you really want to learn this material, show what YOU have done; ask questions about what YOU need to know to be able to solve the problem at hand.

Answer 12

its .6 not 6

Answer 13

yeah, I wrote 0.6 It might be tough to see.

Answer 14

alright @richyw and ok @mathmale

Answer 15

@dragonknight326 : thank you for understanding. @richyw's sketch is REALLY nice. Can you use that sketch to figure out what you have to do to find the approx. surface area of the pencil?

Answer 16

so you really have three surface areas to calculate here right? you need the area of the cone , which is the lateral surface area of the cone, the area of the side of the cylinder, and the area of the blunt end of the pencil.

Answer 17

yes i can thank u for the help @mathmale and @richyw

Answer 18

Perhaps you and richyw could discuss how to determine the surface area of a cone. I've forgotten and would have to do an Internet search for "surface area of a cone" to do that.

Answer 19

I don't know how do derive it without using calculus @mathmale I would assume this is something that is memorized for elementary geometry?

Answer 20

ive tried many things i keep using pie and i think its the right way buy im not sure i keep geting the wrong answer

Answer 21

@richyw

Answer 22

@richyw: Right: the formula for the area of a cone needs to be derived through calculus. So, in this case, your doing an internet search for this geometry formula was entirely appropriate. Use the formula for "lateral surface area." Please discuss what "lateral surface area" means. Many thanks.

Answer 23

should it be cut .6 in hal .3 x .3 =.9 x 3.14 then multiply 2 and 15?

Answer 24

The "lateral surface area" formula that richyw found is\[A = \pi*r*\sqrt{(r ^{2}+h^2)}. \] I would NOT expect you to have memorized this, but you'd need to know how to find it through an Internet search.

If you'll take your r and h values for this cone, and substitute them into the surface area formula, you'll end up with the surface area of the point.

Next, find the surface area of the sides of the pencil.

Last, find the surface area of the flat end of the pencil.

add all these areas up. Good luck.

Answer 25

Thank you for asking. Good question! But the diagram richyw provided shows that the radius, r, of the point of the pencil and of the body of the pencil is 0.6.

Answer 26

yes. I messed up. it should be 0.3cm. I desperately was trying to say this but lost connection :)

Answer 27

but while I had no connection I made a nice 3D image of the pencil just for fun. This one is to scale :)

Answer 28

holy. sorry I had no idea how big that image was. hopefully it's not people like me making OS so slow. Either way, using 0.3 you should get an answer that is one of those multiple choice options. If you don't, then post your work here and I can look at it.

Answer 29

.3 x .3 x 3.14 x2 x15 = x

Answer 30

is this the formation @richyw

Answer 31

I don't really understand what you just typed. try using the equation editor. but you will need a sum of three values, and I see no addition signs in there...

Answer 32

I'd suggest you both break up the problem into two parts.
1) Find the surface area of the point.
2) Find the surface area of the sides of the pencil.
3) Find the surface area of the flat end of the pencil.

Re: Equation Editor: just use the regular (+) symbol on your keyboard for "+" in your text. We could discuss this in more depth later on.

Surface area of the sides: (Circumference of the pencil)*(length of pencil without point)
(2Pi r )* ( L )

Could you two finish this, and also find (1) and (3)?

Answer 33

r u sure for the first one