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Mathematics 14 Online
OpenStudy (kamille):

Hello, I need some helo with stereometry. A sphere, which has a radius of 26, is being interesected by a plane, which is away of 10cm from the centre of the sphere. Find the cross sectional area. (I will add a picuture)

OpenStudy (kamille):

OpenStudy (kamille):

@stamp

OpenStudy (kamille):

do you have any ideas, @Meepi

OpenStudy (anonymous):

Yeah, I'm just very bad at the drawing tool tho so it might look really ugly :p

OpenStudy (kamille):

haha dont worry, I am poor at drawing too!

OpenStudy (anonymous):

You need to find the radius of the cross-sectional circle, so start by considering a cross-section of the sphere |dw:1363195972733:dw| We know the equation of the circle \(x^2 + y^2 = r^2\), so in this case it would be \(x^2 + y^2 = 26^2\) We know that \(y = 10\), so we can solve for x and get the radius of the cross section and then calculate the area using \(\pi r^2\)

OpenStudy (kamille):

x stands for radius of a crossed sectional area?THANKS!

OpenStudy (anonymous):

centimeters in this case

OpenStudy (kamille):

12th (the last one in high school)

OpenStudy (anonymous):

It doesn't look like calculus to me

OpenStudy (kamille):

well, I am not from USA, so we don't have lessons like only calculus or algebra, geometry. It is just a topic of our math book: )

OpenStudy (stamp):

Find x |dw:1363196523706:dw|

OpenStudy (stamp):

use x to obtain pi r ^ 2

OpenStudy (kamille):

well, thank you guys for your help a lot!

OpenStudy (stamp):

\[x=\sqrt{26^2-10 ^2}\]\[x=24\]\[area=\pi x^2\]\[area=\pi (24)^2\]

OpenStudy (stamp):

Notice that you dont even need pythagoream theorem because this is a 5:12:13 triangle

OpenStudy (stamp):

5:12:13 triangle compare to 10:x:26 triangle well x = 2(12) = 24

OpenStudy (stamp):

and then yeah area is just based off that radius of 24

OpenStudy (kamille):

well, it is much easier for me to use phytagoream theoremus. what is about that 5:12:13 triangle?

OpenStudy (stamp):

3:4:5 triangles, 5:12:13 triangles it is something u are supposed to know

OpenStudy (kamille):

well, I don't. or maybe we call it in another way

OpenStudy (stamp):

What is h? |dw:1363197013282:dw| h = 5

OpenStudy (stamp):

What is x? |dw:1363197034496:dw| x = 4

OpenStudy (stamp):

What is x? |dw:1363197058054:dw| x = 3

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