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Mathematics 8 Online
OpenStudy (anonymous):

Find the area of the shaded region. Leave your answer in terms of and in simplest radical form.

OpenStudy (anonymous):

OpenStudy (aravindg):

hey saif isnt that an equilateral triangle?

OpenStudy (saifoo.khan):

Yess boss it is.

OpenStudy (aravindg):

for my first my first attempt on this qn i think we should find area of the triangle , area of the sector and area of the circle separately ...let me see if there is a simpler method

OpenStudy (saifoo.khan):

there are two main methods.

OpenStudy (aravindg):

@saifoo.khan which is the other way?

OpenStudy (saifoo.khan):

Find the rest circle + triangle that's easy. second way. find the whole circle, subtract the white part.

OpenStudy (anonymous):

can you guys solve and explain please?

OpenStudy (anonymous):

area of a circle is A=(pi)r^2 notice in this case we know r = 12 so therefore our area of a circle is A=144pi

OpenStudy (anonymous):

now we need to subtract this by that white part which iss

sam (.sam.):

@saifoo.khan use first way is easier

OpenStudy (saifoo.khan):

@.Sam. , agree.

OpenStudy (saifoo.khan):

We can use simple P1 math to solve by second method too. ;)

sam (.sam.):

there are 6 sectors 6 times 60 =360 degree so, we dont use 6 sectors but 5, then , 5 sectors + triangle = shaded area

OpenStudy (saifoo.khan):

@.Sam. , check this out: http://openstudy.com/updates/4fced71be4b0c6963ad9ed4b

OpenStudy (aravindg):

@saifoo.khan i think we nned area of sector too

sam (.sam.):

\[\text{Sector}~A=\frac{1}{2}r^2 \theta\]

OpenStudy (saifoo.khan):

That will give you perfect answer. no worries. :)

OpenStudy (aravindg):

yep

sam (.sam.):

5 sectors + triangle = shaded area \[5(\frac{1}{2}(12)^2(\frac{\pi}{3}))+\text{Area of \triangle}\]

OpenStudy (anonymous):

area of a circle is A=144pi \[area of unshadeed part = r ^{2}[\pi \theta/360^{0} - \sin \theta/2]\] =144{[22/7*60/360 ] - [(sqrt 3/2)/2]} area of circle - area unshaded is =area of shaded part

OpenStudy (anonymous):

120 pi - 26sqrt3

OpenStudy (anonymous):

so which one is it? (120+ 6 sqrt 3)m² (142+ 36sqrt 3)m² (120+ 36 sqrt 3)m²

OpenStudy (anonymous):

sorry 120 pi -36sqrt3

OpenStudy (anonymous):

you mean + not -?

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