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Maths, Addmaths and Statistics: Post your doubts here!

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Maths Paper 1 Nov Dec 2010 Q27 (c) ,my answer comes 30 but in MS its 7.5 ..Plz Explain
Let the radius be r

Therefore Length of one arc : (40/360)*2*3(pie=3)*r = (2/3)r

Therefore Total length of sector : (2/3)r + 2r

Implying that all 3 = 3 ((2/3)r+2r)
=2r + 6r
=8r

Now 8r=60
r=7.5

Hope it helps
 
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Maths Paper 1 Nov Dec 2010 Q27 (c) ,my answer comes 30 but in MS its 7.5 ..Plz Explain
yes answer is 7.5....
length of the wire= length of the 3 arcs + (6r)
60 cm = ( 3 x 2 x pi x r x 40/360) + 6r
60 =( 18r x 1/9)+ 6r
8r= 60
r= 7.5
:)
 
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share please...:D
well it was a bit easy... v vl take the sector from an angle of 60 nd that will make an equilateral triangle nd then take out the arc length plus the small arcs taking theta 120 nd the radius 5 cm. same goes for the area... except u vl have to change some steps.... of course..
 
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June 2003 Q7 part a maths paper find out the surface area of the shape reply asap

shape.png
look at the image u have to find the shaded surface area. therefore u can find the area of whole image and then divede by two or find one by one as done below:-

area of half cylinder = (2 x pie x r^2 )/2 + 2 x pie x r x lenght
therefore =254.5 +508.9 => 763.4

surface area of quarter sphere=( 4 x pie x r^2)/4 => pie x r^2
therefore = 508.9

now add app all areas => 508.9+763.4=> 1272.3

hope u got undertsand!!!
 
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For sums like solve cos 3x= -0.2 why do they take cos inverse as 0.2 instead of -0.2??
which question are u referring to? coz they take cos inverse -0.2 as -0.2, but the method of doing this is taking the inverse of the alpha angle eg: cos inverse 0.2, then the alpha angle is looked, if originally it was negative, then we look in the quadrants where cos is negative (2nd and 3rd quadrant)
 
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which question are u referring to? coz they take cos inverse -0.2 as -0.2, but the method of doing this is taking the inverse of the alpha angle eg: cos inverse 0.2, then the alpha angle is looked, if originally it was negative, then we look in the quadrants where cos is negative (2nd and 3rd quadrant)
Now I get it thanks...my doubt is cleared
 
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Why don't cambridge release specimen papers this year :(((

Its only released when syllabus or paper format is changed this year it wasnt :D

,
View attachment 6954
look at the image u have to find the shaded surface area. therefore u can find the area of whole image and then divede by two or find one by one as done below:-

area of half cylinder = (2 x pie x r^2 )/2 + 2 x pie x r x lenght
therefore =254.5 +508.9 => 763.4

surface area of quarter sphere=( 4 x pie x r^2)/4 => pie x r^2
therefore = 508.9

now add app all areas => 508.9+763.4=> 1272.3

hope u got undertsand!!!

Have u checked ur answer with the ms because i think theres something fishy in it :p
 
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