Math Is Fun Forum

clara951

Guest

Math, Reviews about finding areas of Cylinders and Polygons

Hello again,

First of all, I tried to register in this forum and it told me that I need to wait for a password that would come to my email, but nothing ever came so I'm still not logged in at this forum.

I want to thank Bob for last time he helped me with a math problem, your method was very useful.

These days I'm stuck with two exercises that I have no idea how to solve.

The first One:
5. Find the area of the figure below by dividing it into 3 distinct shapes. For example, you cannot use two rectangles or a rectangle and a square. Use the areas of these three shapes to find the total area. (2 pts.)

This is the image: https://www.compuhigh.net/classes_2/geometry/lesson24/img-1-L24_N5.jpg

I tried first to split it into a right triangle and two rectangles. But I don't have any solution for it. Could you please give me a few hints?

The second one:
6. Find the surface area and the volume of the figure below. Break your work down into three sections: Cone, Cylinder, and Sphere. Show the work for both the surface area and volume. Then find the total surface area and volume. Use 3.14 for π. R (3 pts.)

This is the image: https://www.compuhigh.net/classes_2/geometry/lesson24/img-2-L24_N6.jpg

I'm having a few problems regarding this exercise. It would be great if you could point at what I'm doing wrong.

I first figured the surface area and the volume of the cone, then I continued with the surface area and the volume of the hemisphere and in the end, I solved for the cylinder's surface area and the volume. In the last step, I added all the Surface Areas together and got my answer. The only thing I don't understand is why is a side given for the hemisphere because I can solve the surface area of the hemisphere even without it. Also, it is given that the side length of all the figures is 25inchs. So to find the height of my cylinder I subtracted 25 with 8 and got 17 as my cylinder's height. Is that correct?

It would be great if you could answer right away because it's been a week!

Thank you in advance,

Mathegocart

Member

Registered: 2012-04-29

Posts: 2,226

Re: Math, Reviews about finding areas of Cylinders and Polygons

Hello Clara,
I have no idea if you realize this, but we are unable to access the images in question(it appears there is a login system). Also, there is a dedicated tag for images, img, so use that in the future.

Thanks,
Mathegocart.

Last edited by Mathegocart (2021-04-25 02:01:28)

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The integral of hope is reality.
May bobbym have a wonderful time in the pearly gates of heaven.
He will be sorely missed.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,580

Re: Math, Reviews about finding areas of Cylinders and Polygons

hi clara951

Welcome back.  I'm glad to have been able to help you.

The forum has recently been switched to a new server and there have been a few hiccups, with some things not working.

The new members process is one such.  It has been sorted now, we hope, so please
try again.

Folk who pay money to CH can access all their worksheets but other cannot I'm afraid.  Maybe you can describe the situation like this: eg.  There's a rectangle I'll call it ABCD.  Joining onto the side AB is a triangle ABE where E is a new point.  Angle AEB looks like it is 90.  etc etc.

Hopefully I'll be able to follow your instructions to make the drawing.  Then I'll post it to check with you that we're talking about the same thing.

I'm going to read what you've said anyway and see if I can figure out what the diagram is. Back soon.

Later edit:  I cannot figure out the shape for the first question.  You'll have to give some more details, and measurements.

For the second I'm wondering if there's a cylinder with a cone joined at one end and a hemisphere at the other.  So they all have the same radius.  Then I'd need to know the length of the cylinder, and the height of the cone.  For a cone it is also necessary to know the slant height in order to calculate the surface area.

So, if that's the correct object you can just tell me all the measurements.

Bob

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob