Mathematics 7 Online
OpenStudy (anonymous):

find the surface area of the space figure. 28 ft by 36 ft.

OpenStudy (anonymous):

its a cylinder if that helps

OpenStudy (anonymous):

plz help!

OpenStudy (anonymous):

Surface Area = Areas of top and bottom +Area of the side Surface Area = 2(Area of top) + (perimeter of top)* height Surface Area = 2(pi r 2) + (2 pi r)* h

OpenStudy (anonymous):

a cylinder is made up of 3 parts: 2 circles are each end, and a rectangle wrapped around the circles for the main part

OpenStudy (anonymous):

it is a 3dimenton figer

OpenStudy (anonymous):

Surface Area of a Cylinder = 2 pi r 2 + 2 pi r h

OpenStudy (anonymous):

ok, but why is that the case? because there are 2 circles (for the 2 * pi*r^2), then a rectangle which constitutes the middle, the rectangle has height=h, and the width of the rectangle equals the circumference of the circle, which is 2*pi*r

OpenStudy (anonymous):

so the area of the two circles is: 2* (pi*r^2) area of the rectangle is: h * width, where width = 2*pi*r, so -> h*(2*pi*r)

OpenStudy (anonymous):

(h is the height of the cylinder, r is the radius of the top)

OpenStudy (anonymous):

so as glenn pointed out: Surface Area of a Cylinder = 2 pi r 2 + 2 pi r h

OpenStudy (anonymous):

which is area of both circles plus the area of the rectangle

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

hold on wrong chat

OpenStudy (anonymous):

that i am get ing i have not did this in a long time

OpenStudy (anonymous):

Surface Area = 2(pi r 2) + (2 pi r)* h

OpenStudy (anonymous):

yes..

OpenStudy (anonymous):

ok?

OpenStudy (anonymous):

sorry was gone

OpenStudy (anonymous):

dk?

OpenStudy (anonymous):

help?

OpenStudy (anonymous):

yes with what

OpenStudy (anonymous):

???

OpenStudy (anonymous):

same question

OpenStudy (anonymous):

Surface Area = 2(pi r 2) + (2 pi r)* h

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