Sunday, March 7, 2010

Surface Area Growing Post , JerickR873

Ok this is my growing post for math , i will be showing yo what a rectangular prism , triangular prism , and a cylinder looks like and nets , also how to solve for Total Surface Area (TSA)

1st the Rectangular Prism

the formula for the rectangular prism is:
l x w = a

one way to find TSA for a rectangle is to find the area of the side , front , and top then you just times those by two because of their opposite side

Top

l x w = a
20 x 2 =a
40x2=ax2
80=ax2

Side
l x w = a
20 x 2 = a
40 x 2 = ax2
80 = a x 2

Front

l x w = a
20 x 20 = a
400 x 2 = a x2
800 = a x2

TSA = 800+80+80
TSA= 960 cm2

2nd is the Triangular Prism

Formula
b x h = a
l x w = a
I like to find all sides just like the rectangular prism and add up all the sides

Front
b x h = a
12 x 12 = a
144 x 2=a
288 = a x2

Bottom
l x w = a
12 x 5 = a
60 = a

Back
l x w = a
12 x 5 = a
60 = a

Top
l x w = a
1o x 5 = a
50 = a

TSA= 50 +60 + 60 + 288
TSA= 458 cm2

3rd the Cylinder

Formulas
d divided by 2 = r
pi R 2 = a
pi D = c
l x w = a

For cylinders , you need to find the area and circumference of a circle and times that by 2 , for the other end , and then for the rectangle its the circumference of the circle that is the width of the rectangle

pi D = C
3.14 x 15 = c
47.1 = c

d/2 = r
15/2=r
7.5= r

pi R 2 = a
3.14 x 7.5(2) = a
3.14 x 56.26 = a
176.67 x 2 = a
353.34= a

l x w = a
20 x 47.1 = a
942=a

942 + 353.54 =1295.34 cm2

Thanks YOU FOR READING MY POST

PLEASE COMMENT ON ANYTHING THAT I DID WRONG OR
THINGS I CAN DO BETTER

hannah873

Hi Jerick. You've done great job. You've even put things that weren't necessary and that's really great. One thing you got wrong is the formula for the triangle. It's base times height divided by two. That's all. Really good job though. Keep it up.

ChristineAnne8-73

Great job jerick. like what hannah said. Its divided by 2 not times 2. So, the answer should be 72 (:

Abigail8-73

Good job Jerick (: I agree with them. The formula for the triangular prism is bxh divided by 2 not multiply by 2. (: Thats ok though. What i like about your post is that its so neat and organize. (y) Good job again

Camille873

nice job jerick, i lied how you put some pictures and i got kinda confused when you explained how to do it . great job on the video and to your blog post