« previous next »
Pages: 1 ... 6 7 [8] 9 10 ... 80   Go Down

Author Topic: IGCSE MATHS Doubts  (Read 130283 times)

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: IGCSE MATHS Doubts
« Reply #105 on: May 05, 2010, 07:05:32 pm »
Ur welcome.
Logged
divine intervention!

Offline Saladin

  • The Samurai
  • Honorary Member
  • SF V.I.P
  • *****
  • Posts: 6530
  • Reputation: 59719
  • Gender: Male
  • I believe in those who believe in me
    • Student Tech
Re: IGCSE MATHS Doubts
« Reply #106 on: May 05, 2010, 07:06:50 pm »
I think Aadi is rite in his method. dnt hav time to check exact details.
Logged

Offline Baladya

  • meawwwww hao hao >.<
  • SF Geek
  • ****
  • Posts: 554
  • Reputation: 681
  • Gender: Male
Re: IGCSE MATHS Doubts
« Reply #107 on: May 05, 2010, 07:19:11 pm »
Quote from: haris94 on May 05, 2010, 06:47:31 pm
V1/V2 = (l1/l2)3

so
5/v2 = (2/0.4)3
v2 = 5*(0.4)3
           (2)3

v2 = 0.04m3

0.04*1000
=40 cm3

OMG HOW DID I FORGET THE RATIO THING  ??? ??? Anyway thanks man ;)
Logged
Looks like i ran out of cool signatures :|

Offline haris94

  • SF Senior Citizen
  • *****
  • Posts: 930
  • Reputation: 984
  • Gender: Male
Re: IGCSE MATHS Doubts
« Reply #108 on: May 05, 2010, 07:24:33 pm »
lol.....no probs
Logged
WHAT WE DO IN LIFE ECHOES AN ETERNITY

Offline The Golden Girl =D

  • Without Allah I'm nothing <3
  • Honorary Member
  • SF Overlord
  • *****
  • Posts: 13757
  • Reputation: 65532
  • Ain't Nothin worth your tears =D
    • www.thegoldengirl157.blogspot.com
Re: IGCSE MATHS Doubts
« Reply #109 on: May 06, 2010, 06:03:16 am »
Quote from: contraentry on May 05, 2010, 04:30:18 pm
This is from November 1990 P4

@The golden girl: You're welcome!

You need to do the "180 - 54" because the question says it is an obtuse angle, and the Sine function proves : Sin 54 = Sin(180-54)

Moreover, 54 is not an obtuse angle, an obtuse angle is defined as an angle being greater than 90 and less than 180.

thx again !!
Logged
Verily, in the remembrance of Allah do hearts find rest(13:28)

Please, Don't forget to Include GG in your Prayers =D

Offline The Golden Girl =D

  • Without Allah I'm nothing <3
  • Honorary Member
  • SF Overlord
  • *****
  • Posts: 13757
  • Reputation: 65532
  • Ain't Nothin worth your tears =D
    • www.thegoldengirl157.blogspot.com
Re: IGCSE MATHS Doubts
« Reply #110 on: May 06, 2010, 06:04:57 am »
Quote from: A@di on May 05, 2010, 04:32:48 pm
Ok if u solve it using the sine method. You get 54 degree. However they say its obtuse which means sine x = 0.809 , x =/= 54.

in such situations, u have to use the trigonometric rule sine x = sine 180-x rule  to find any other angle whose sine is 0.809

thus, 180-54 = 126. sine 126 = 0.809

Answer : 126 (Obtuse)

i didn't know that such a rule "sin =180 - 54" can come in a traingle question.....that's y i didn't even think of this rule ..........thx !!
Logged
Verily, in the remembrance of Allah do hearts find rest(13:28)

Please, Don't forget to Include GG in your Prayers =D

Offline LM

  • SF Immigrant
  • **
  • Posts: 91
  • Reputation: 171
  • Gender: Female
Re: IGCSE MATHS Doubts
« Reply #111 on: May 06, 2010, 07:47:42 am »
Hey Guys...
I have billion of question I don't understand...
Could you please help me?
here are the question...

1. Carla estimates the length of the wall to be 25 m and the height to be 2 m.Paolo tells her that the length is 25 m correct to the nearest   5 m and the height is 5 m correct to the nearest 10 centimetres. Complete the statements below.
(a) ............m ? length of the wall < ...........m
(b) ............m ? height of the wall < ...........m
and everytime this kind of question come up, I never understand hooq to do it....

2.
Logged
Having you in my dreams its like having my worst nightmares.

Offline Snake

  • SF Immigrant
  • **
  • Posts: 117
  • Reputation: 183
  • Gender: Male
Re: IGCSE MATHS Doubts
« Reply #112 on: May 06, 2010, 08:23:52 am »
20M=<Length of wall<30M
1.9M=<Height of the wall<5.1M

That should be right
Logged
-Once the game is over,the king and the pawn go back in the same box-

Offline Dark Prince

  • SF Immigrant
  • **
  • Posts: 60
  • Reputation: 86
  • Gender: Male
Re: IGCSE MATHS Doubts
« Reply #113 on: May 06, 2010, 08:46:25 am »
hey deres another Qs:

Q- Two men, John and Peter, can paint a house in 10 days. John alone can paint the house in 15 days. How long will Peter take to paint it alone?
Logged

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: IGCSE MATHS Doubts
« Reply #114 on: May 06, 2010, 09:11:51 am »
10/15 + 10/x = 1

10x + 150
---------    =   1
     15x

10x + 150 = 15x

5x = 150

x = 150/5 = 30

30 days.

Im not sure abt this though
Logged
divine intervention!

Offline haris94

  • SF Senior Citizen
  • *****
  • Posts: 930
  • Reputation: 984
  • Gender: Male
Re: IGCSE MATHS Doubts
« Reply #115 on: May 06, 2010, 09:29:30 am »
can u pls explain how u got your first step:
10/15 + 10/x = 1
Logged
WHAT WE DO IN LIFE ECHOES AN ETERNITY

Offline Vin

  • SF V.I.P
  • ********
  • Posts: 7914
  • Reputation: 52609
  • Gender: Male
    • Theory of Life - A new skew.
Re: IGCSE MATHS Doubts
« Reply #116 on: May 06, 2010, 09:41:06 am »
Quote from: A@di on May 06, 2010, 09:11:51 am
10/15 + 10/x = 1

10x + 150
---------    =   1
     15x

10x + 150 = 15x

5x = 150

x = 150/5 = 30

30 days.

Im not sure abt this though


yup its right...i hav another method..

john n peter 10days =>   1 house
                  1 day  =>    1/10 house

john in 1 day  =>  1/15

so,  one day of john + peter =  one day of  john n peter together

1/15  +  x  =  1/10
(L.C.M)
 
1 + 15x
---------    =   1/10
   15

1  + 15x = 15/ 10

15x  =  15/10  -1
(LCM on right)

15x = 1/2

x = 1/30

peter paints 1/30 of house 1 one day...so he takes 30 days to paint one house :) :)

always try to convert any work to 1 day n solve..i find this method easy tho..dunno abt others..  :)
                   
Logged

Offline Vin

  • SF V.I.P
  • ********
  • Posts: 7914
  • Reputation: 52609
  • Gender: Male
    • Theory of Life - A new skew.
Re: IGCSE MATHS Doubts
« Reply #117 on: May 06, 2010, 09:44:25 am »
Quote from: haris94 on May 06, 2010, 09:29:30 am
can u pls explain how u got your first step:
10/15 + 10/x = 1

days for..(time taken for)

john+peter/john  +  john+peter/peter  =  1 house

Logged

Offline haris94

  • SF Senior Citizen
  • *****
  • Posts: 930
  • Reputation: 984
  • Gender: Male
Re: IGCSE MATHS Doubts
« Reply #118 on: May 06, 2010, 09:53:17 am »
Quote from: ~VIN1094~ on May 06, 2010, 09:44:25 am
days for..(time taken for)

john+peter/john  +  john+peter/peter  =  1 house


hmm...yea got it Thanks
nice method By the way
 
Logged
WHAT WE DO IN LIFE ECHOES AN ETERNITY

Offline Baladya

  • meawwwww hao hao >.<
  • SF Geek
  • ****
  • Posts: 554
  • Reputation: 681
  • Gender: Male
Re: IGCSE MATHS Doubts
« Reply #119 on: May 06, 2010, 10:03:40 am »
This isn't only in triangles. Its also in Sine and Cosine rule. Sometimes they ask u to write the two answers for sinx under for example 180.. search google for the sine and cosine 'curve' for maths and u will understand what m saying.
Logged
Looks like i ran out of cool signatures :|
Pages: 1 ... 6 7 [8] 9 10 ... 80   Go Up
« previous next »