Maths paper 2.. 2012!!

svenas

svenas

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IGCSE O/L student said:
dat typ of question is not dere for our level. if a question appears lyk dat, da formula will b given to use. it came in M/J 2011
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Thank u for taking ur time to answer me...but my problem in this question (M/J 2011) is that when they gave the formula and asked to find the sum of even numbers, they found for the first 4oo and then multiplied it by two, which I didn't understand so plz explain me this step
 
IGCSE O/L student

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svenas said:
Thank u for taking ur time to answer me...but my problem in this question (M/J 2011) is that when they gave the formula and asked to find the sum of even numbers, they found for the first 4oo and then multiplied it by two, which I didn't understand so plz explain me this step
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dats coz we wnt da sum of da first 400 even numbers.
2 is 1 multiplied by 2, ryt? 4 is 2 multiplied by 2, ryt? so da sum for the first 400 numbers multiplied by 2 givs da ans 4 da first 400 even numbers.
 
svenas

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IGCSE O/L student said:
dats coz we wnt da sum of da first 400 even numbers.
2 is 1 multiplied by 2, ryt? 4 is 2 multiplied by 2, ryt? so da sum for the first 400 numbers multiplied by 2 givs da ans 4 da first 400 even numbers.
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yeah I got u... U know that if I take A* this would be due to ur help really cauz u r solving all my doubts...
Anyway a question came up which asked me to find the obtuse angle ABC in (o/n 2011 p41 q6)...I used normally the sine rule and found the answer as 48.5 degrees, but what they did is that they subtract 180-48.5 and got 131.5 ....THIS REALLY MADE ME SAD cauz this is the first time this question I faced and I cant understand it at all so plz make it clear for me and thanks
 
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svenas said:
yeah I got u... U know that if I take A* this would be due to ur help really cauz u r solving all my doubts...
Anyway a question came up which asked me to find the obtuse angle ABC in (o/n 2011 p41 q6)...I used normally the sine rule and found the answer as 48.5 degrees, but what they did is that they subtract 180-48.5 and got 131.5 ....THIS REALLY MADE ME SAD cauz this is the first time this question I faced and I cant understand it at all so plz make it clear for me and thanks
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awww! dats swt of u. but will b due 2 ur efforts as well.
sin x=sin(180-x)
so, sin (48.5)=sin(180-48.5)
thus, da value of da obtuse angle is 131.5
 
svenas

svenas

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IGCSE O/L student said:
awww! dats swt of u. but will b due 2 ur efforts as well.
sin x=sin(180-x)
so, sin (48.5)=sin(180-48.5)
thus, da value of da obtuse angle is 131.5
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I didn't get u that much, I'm sorry , try to explain it to me again plz, cauz this is the first time I solve this type of question
 
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IGCSE O/L student said:
awww! dats swt of u. but will b due 2 ur efforts as well.
sin x=sin(180-x)
so, sin (48.5)=sin(180-48.5)
thus, da value of da obtuse angle is 131.5
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In addition, I also wants to know that the sine and cosine rules only give acute angles ryt???
 
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svenas said:
I didn't get u that much, I'm sorry , try to explain it to me again plz, cauz this is the first time I solve this type of question
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ur ans is 48.5, ryt?
in a sin curve, dere r two x values for each y value.
sin x=sin(180-x)
x=48.5. da value for sin 48.5 is 0.7489557208....
n da value for sin(180-48.5) is also 0.7489557208....
so da angle cn be either 48.5, or 180-48.5, which is 131.5.
 
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