:mad: so frustrated trig C2 With worst drawin ever included Watch

Dark and Lovely
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#1
Report Thread starter 12 years ago
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i am so pissed off

i went through the review exercise doing questions without writing em down to see how easy they are

i did this question in my head got it right but cant remember for the life of me how i did it!!!

A Flower bed is arranged as follows Triangle DEF is an equilateral triangle of side 8m Arcs EF, FD, DE have radii of 8m and centres D, E and F respectively

find the area of the flower bed correct to the 0.1m


ok ive got the right answer but with dodgy workings that dont make sense
thetha=pi/3
i did 1/2 r^2 x thetha then x 3 as of 3 diff sectors= 100.53

then i took away from that 64x sinxpi/3

=45.1-right answer!

but thats all BS has any1 got the right way of doing this?!
please
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arktos
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area of a the triangle is 1/2 x 8 x sqrt 48 = 4 sqrt 48
area of sector = 1/2 r^2 theta , since equi triangle theta = pi/3 r = 8
area sector = 1/2 x 64 x pi/3

area of each chunk not in triangle is therefore 4 sqrt 48 - 32 pi/3
area of three outside chunks = 12 sqrt 48 - 32 pi
area triangle = 4 sqrt 48

total area of flowerbed = 12 sqrt 48 - 32 pi + 4 sqrt 48
= 16 sqrt 48 - 32 pi
= 10.3 something

no idea whatsoever about how correct this is.
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Dark and Lovely
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(Original post by arktos)
area of a the triangle is 1/2 x 8 x sqrt 48 = 4 sqrt 48
area of sector = 1/2 r^2 theta , since equi triangle theta = pi/3 r = 8
area sector = 1/2 x 64 x pi/3

area of each chunk not in triangle is therefore 4 sqrt 48 - 32 pi/3
area of three outside chunks = 12 sqrt 48 - 32 pi
area triangle = 4 sqrt 48

total area of flowerbed = 12 sqrt 48 - 32 pi + 4 sqrt 48
= 16 sqrt 48 - 32 pi
= 10.3 something

no idea whatsoever about how correct this is.
thanks but the answer im looking for is 45.1
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arktos
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(Original post by arktos)
area of a the triangle is 1/2 x 8 x sqrt 48 = 4 sqrt 48
area of sector = 1/2 r^2 theta , since equi triangle theta = pi/3 r = 8
area sector = 1/2 x 64 x pi/3

area of each chunk not in triangle is therefore 4 sqrt 48 - 32 pi/3
area of three outside chunks = 12 sqrt 48 - 32 pi
area triangle = 4 sqrt 48

total area of flowerbed = 12 sqrt 48 - 32 pi + 4 sqrt 48
= 16 sqrt 48 - 32 pi
= 10.3 something

no idea whatsoever about how correct this is.
edit - so the area of chunk not in triangle = 32 pi/3 - 4 sqrt 48
area of the outside chunks = 32 pi - 12 sqrt 48
area triangle = 4 sqrt 48

total area flowerbed = 32 pi - 8 sqrt 48 = 45.1 ish
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