EMMANUELS BLOG POST?!

In today's math class, we worked on calculating the area of prisms and cylinders. We also worked a bit on finding the volume of a prism.

To calculate the area of faces on a cylinder, you must use the formulas:
πr² (pi x radius squared) AND 2πrh (2 x pi x radius x height)

For finding the area of the top face of a cylinder you must use the formula:
πr²




For example:
The radius of the cylinder is 5cm

π r ²(pi x radius squared)

(3.14) (5²) I got 3.14 from pi, and 5 because that is the radius.

(3.14) (25) After squaring 5, you are left with 25.

After multiplying 3.14 and 25, the top face of a cylinder would be:
78.5cm²

You also need to know the formula for finding the area of the rectangle in a cylinder. The formula for that is:
2πrh (2 x pi x radius x height)

For example:
A cylinder has a radius of 4, and a height of 3.

2 π r h (2 x pi x radius x height)

2x(3.14) (4) (3) 3.14 represents pi, 4 is the radius, and 3 was the height

(6.28) (4) (3) I got 6.28 after multiplying 3.14 by 2

(25.12) (3) 25.12 was from multiplying 6.28 by 4

75.36cm² is the area of the rectangular face on a cylinder

For finding the surface area of a prism, you will need the following formula:
2(lxw)+ 2(lxh)+ 2(hxw)
(You add the two because there are 3 pairs of opposite sides with the same area)



For example:
A prism has a length of 5, a height of 2, and a width of 3, what is the surface area?

To start off, you would need the formula:
2(lxw)+ 2(lxh)+ 2(hxw)

Then replace the variables with their numbers:
2(5x3)+ 2(5x2)+ 2(2x3)

One at a time you multiply the brackets:
2(15)+ 2(10)+ 2(6)

Once you've done that, you multiply the lengths by 2:
30+20+12

Then you find your answer!
62cm²

Now that were done.. just kidding we have to learn volume now.

To find the volume of a prism, you must use the formula:
WxDxH (width x depth x height)
(though they might not always give you the exact numbers)

For example:
A prism has a width of 2, a depth of 2, and a height of 2.

Start of with your fancy formula:
WxDxH

Fill in the numbers:
2x2x2

MULTIPLY:
8cm³(volume is always cubed)

Thank you for reading my scribe post which took 5 hours.

WANT MORE PRACTICE? VISIT THESE SITES www.shodor.org/interactive/activities/surfaceareaandvolume www.mathguide.com/lessons/SurfaceArea.html

PLAY MORE TUTPUP CHILDREN

I choose JERIC for the next scribe.. just kidding it's actually
ARGIE