#1
please help me with this math problem...

The central angle of a sector has a measure of 3pi/5 (Three Pi divided by Five) in a circle of radius 4 cm. Find the area of the sector. Round to the nearest hundredth.

I believe the formula used for this would be s=r0, 0 being theta (just a sign for the angle measure)

i know that the answer to this problem is 15.08 cm^2 , I just cant figure out the work for it. so if you could please walk me thru the steps....
#2
you got the formula wrong dude.
area of sector = (angle of sector)/2 * r^2 , where r is the radius

if you need help with how this formula came about, you can just ask and i'll give u a derivation for it.
#4
Quote by nine01n
does the angle of sector need to be in radians or degrees?


just to say:

r0 is the right formula, and it needs to be in radians.
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#5
its in radians

so for this problem (3pi/5) /2 * 4^2 = 15.0796 which is when rounded off, the answer your looking for
#6
Quote by Sol9989
just to say:

r0 is the right formula, and it needs to be in radians.



ok to clear things up here. r0 is the formula for circumference of sector. not area.
and it has to be in radians as well

cheers
#7
Area of Circle = pi r^2
Ratio of Sector to Full Circle = (3pi/5) / (2pi) = 3/10

Area of Sector = (3/10) * pi (4 cm)^2
#8
pfft no need to be so pretentious about it.

-1 respect point.

it's 3am, i'm allowed to forget what i did 3 years ago.
"And after all of this, I am amazed...

...that I am cursed far more than I am praised."
#9
relax dude. im just clearing things up. no need to get worked up. we all forget things that we have learnt.
#10
s=r[(0)(2)]/0
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#11
Quote by avenger86
ok to clear things up here. r0 is the formula for circumference of sector. not area.
and it has to be in radians as well

cheers


If you want to be technical about it, s = r0 is actually arc length. Circumference describes the boundary or perimeter of a closed circular area.
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Last edited by lespaulrocks39 at Apr 29, 2008,
#12
Quote by lespaulrocks39
If you want to be technical about it, s = r0 is actually arc length. Circumference describes the boundary or perimeter of a closed circular area.



you are right about that. the term arc length just left me for a moment.