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UnknownError
March 12th, 2013, 04:57 PM
Okay, I know how to find the angle if I have the arc. And I know how to find the arc if I have the angle. But idk what to do now lol. Can someone help, I've copied the question down completely on the picture:
http://www.virtualteen.org/forums/attachment.php?attachmentid=5292&stc=1&d=1363125432

I need the working aswell pls.
kye.
March 12th, 2013, 05:32 PM
Okay, I know how to find the angle if I have the arc. And I know how to find the arc if I have the angle. But idk what to do now lol. Can someone help, I've copied the question down completely on the picture:
image (http://www.virtualteen.org/forums/attachment.php?attachmentid=5292&stc=1&d=1363125432)

I need the working aswell pls.

The ratio of the unknown angle to 360 degrees should be the same as the ratio of the area of the sector to the area of the circle.

First, find the area of the circle of radius 10cm:

A = pi(10)^2 = 314.16

Then solve the following proportion:

x/360 = 80/314.16

x = 91.67 degrees
UnknownError
March 12th, 2013, 05:40 PM
The ratio of the unknown angle to 360 degrees should be the same as the ratio of the area of the sector to the area of the circle.

First, find the area of the circle of radius 10cm:

A = pi(10)^2 = 314.16

Then solve the following proportion:

x/360 = 80/314.16

x = 91.67 degrees

http://celebquote.com/wp-content/uploads/2012/12/tumblr_m8cjpjAWht1rch835o1_500.gif

thank youuuuuu.
kye.
March 12th, 2013, 05:45 PM
image (http://celebquote.com/wp-content/uploads/2012/12/tumblr_m8cjpjAWht1rch835o1_500.gif)

thank youuuuuu.

Haha You're welcome :D
UnknownError
March 12th, 2013, 05:53 PM
Never mind edited :)))
kye.
March 12th, 2013, 06:48 PM
wait, one more question. how does



work out?

It's a proportion :P cross multiply and division,

http://i1301.photobucket.com/albums/ag110/kyeblack18/DSC_0178_zps60e6b63a.jpg

I'm pretty confident about the answer :)

By the way, let me know if you get it right!

Please use the Edit button to add something instead of double posting. ~TheMatrix
UnknownError
March 13th, 2013, 07:01 PM
By the way, let me know if you get it right!

Turns out it was for Thursday not Wednesday, but I will. :)
Magical
March 15th, 2013, 06:12 AM
Turns out it was for Thursday not Wednesday, but I will. :)

Just by the way - an approach I prefer:

80 (area)= (x/360) (the part of the circle that actually exists) πr^2 (area of a triangle)
80 = 100πx/360
80 x 360 = 100πx
80 x 3.6 = πx
288 = πx
288/π = x

x = 91.67 (4 significant figures)