Find the measure of an arc given that the shaded region has an area of 45.55 square centimeters if the radius is 6?
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OpenStudy (anonymous):
What is area of arc?
OpenStudy (anonymous):
OpenStudy (anonymous):
that shows the diagram
OpenStudy (anonymous):
arc is the same as the angle given
OpenStudy (anonymous):
there is no angle
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OpenStudy (anonymous):
Actually, lets start with the area of the circle
OpenStudy (anonymous):
whats 45.55
OpenStudy (anonymous):
the area of shaded region
OpenStudy (anonymous):
do you find area of circle and put 45.55 over area as a proportion to x/360? to find arc angle?
OpenStudy (anonymous):
Yes
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OpenStudy (anonymous):
Then you have x/360 and times this by circumference to get arc length
OpenStudy (anonymous):
is it 144.99?
OpenStudy (anonymous):
Area of circle: 36pi
sector area/circle area: 45.55/36pi ~ 0.403
Circumference: 12pi
Arc length: 12pi*45.55/36pi = 45.55/3 ~15.18
OpenStudy (anonymous):
area of full circle is :
\[\pi r ^{2}\]
the proportion of a sector to the full area is same as the angle of the sector to the full angle:
\[45.55/\pi*6 ^{2}=x/2 \pi\]
from here :
\[x=(45.55*2)/36\]
OpenStudy (anonymous):
notice that x is in radians. To get the answer in centimiters multiply it by 6