Author Topic: IGCSE MATHS DOUBTS HERE !!!!  (Read 39822 times)

Offline Vin

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IGCSE MATHS DOUBTS HERE !!!!
« on: August 24, 2010, 02:26:14 pm »
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elemis

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #1 on: August 31, 2010, 08:15:38 am »
Dude what is this doing here in the bin ? ::)

Moving it back.

Offline WARRIOR

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #2 on: September 15, 2010, 01:54:06 pm »
QUESTION

A golfer hits the ball B a distance of 170m towards a hole H which measures 195m from the tree T to the green.If this shot is directed 10* away from the ttrue line to the hole , find the distance between his ball and the hole.

help, i cant even draw the diagram for this.

ANSWEr is : 40.4 m

Thank You u in advanced
NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa

Offline Vin

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #3 on: September 15, 2010, 02:00:41 pm »
QUESTION

A golfer hits the ball B a distance of 170m towards a hole H which measures 195m from the tree T to the green.If this shot is directed 10* away from the ttrue line to the hole , find the distance between his ball and the hole.

help, i cant even draw the diagram for this.

ANSWEr is : 40.4 m

Thank You u in advanced

Got it. Gimme two mins. ;)

Offline Vin

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #4 on: September 15, 2010, 02:11:06 pm »
[Attachment 1]

Diag 1 is the basic sketch for the situation. We have to find BT.

In this case you are to use the cos rule.

a2 = b2 + c2 - 2bc . cos A

[Attachment 2]

I have renamed to points so that it fits the equation.

a2 = b2 + c2 - 2bc . cos A


a2 = 1952 + 1702 - 2 * 170 * 195 * cos 10

a2 = 66925 - 66300 . cos10

a = \sqrt{66925 - 66300 . cos10}

a = 40.4 m

Hope you get it. I have a bad way of explaining. :P ;)

Offline Deadly_king

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #5 on: September 15, 2010, 02:18:32 pm »
Yeah......i got it as well.

Its a simple triangle with one side 195m and another side 170m with the angle between these two sides being 10*. The question just ask you to find the other side.

Hence you need to use cosine rule. Thats all.

Actually the question is quite misleading but not difficult :)

Offline WARRIOR

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #6 on: September 15, 2010, 02:45:41 pm »
OOH i get it thanks vin ! i owe you a + rep but i have to spread teh love first !

i couldnt draw the diagram so it was a pain 

cheers
NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa

Offline Deadly_king

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #7 on: September 15, 2010, 02:53:50 pm »
OOH i get it thanks vin ! i owe you a + rep but i have to spread teh love first !

i couldnt draw the diagram so it was a pain 

cheers
Dont worry dude........did it for you :)

Offline WARRIOR

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #8 on: September 15, 2010, 08:44:53 pm »
An aircraft flies from its base 200km on a bearing of 162, then 350km on a bearing of 260 , and then returns direcctly to base. Calculate the length and bearing of the journey.

I got the length right but i cant seem to get the bearing  :-\


Also this next question , is attached


Find AE easy
     Angle EAC - easy

The angle of elevation from A ? hard , for me anyway
NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa

elemis

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #9 on: September 16, 2010, 11:55:00 am »
two minutes

elemis

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #10 on: September 16, 2010, 12:11:02 pm »
Question 1

I am assuming you are asking for the homeward journey bearing.

I got 18 degrees first because adjacent angles add up to 180 (162 + 18 = 180).

Next, 360-(260+18) = 82 degrees. The angle adjacent to 100 (100 = 82+18) is 80 degrees (in maroon).

Using \frac{350^2 + 378.2^2 -200^2}{2*350*378.2} we see that cos-1 x = 0.85191.....

hence x =31.5797....  Hence, 80 - angle x = 48.4 degrees

elemis

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #11 on: September 16, 2010, 12:25:58 pm »
Question 2

See pic.

I hope my answers are right :D

Offline WARRIOR

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #12 on: September 17, 2010, 06:50:16 am »
question  1 is right + rep

but question 2


Look at your diagram edited by me

you see the 180 * angle i drew?

yea you find the angle in the small right triangle = 180-90 + 40 = 50*

   Then you find the angle in the middle which is = approx 73.2
   Then 180 - 73.2 + 50 = 56.8

THEN 56.8 - 90 = 33.2 <---right answer !

my teacher said you shouldnt have assumed the whne you drew that line in the middle that you cut the angle exactly into a half , you get the point?

edit : oops i forgot to attaach
« Last Edit: September 17, 2010, 06:53:13 am by Kimo Jesus »
NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa

elemis

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #13 on: September 17, 2010, 06:57:47 am »
Is this a question from your textbook ?

Offline WARRIOR

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Re: IGCSE MATHS DOUBTS HERE !!!!
« Reply #14 on: September 17, 2010, 06:59:07 am »
Is this a question from your textbook ?
yea why?
NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
But it ain't how hard you hit; it's about how hard you can get hit, and keep moving forward-Balboa