Qualification > Math
IGCSE MATHS Doubts
PeaceMaker:
--- Quote from: A@di on May 08, 2010, 06:26:20 pm ---they arent wrong, the ms cant be wrong, which paper is this q from??
--- End quote ---
If your talking to me, i said that i asked the wrong Paper i wrote 2003 when i really wanted the answers of those questions from paper 2005
Vin:
--- Quote from: @d!_†oX!© on May 08, 2010, 06:43:30 pm ---I know you got this already, but i don't mind elaborating :P
90
S | A
180----------0/360
T | C
270
Read the above as follows before starting:
1) A=All +ve , S= Sin +ve , T=Tan +ve , C=Cos +ve
2) This shows the four quadrants, going anticlockwise from 0 to 90 to 180 270 to 360.
3) This means that any angle in a specific quadrant is +ve acc to 1)
So, now coming to your question, the question is talking about sin, which is +ve in the 1st and 2nd quadrant.
The angle already given to us is in the 1st quadrant, so now we know we will get the same value in the second quadrant in the 2nd quadrant (180-x) or the after 360 (360+x)
Taking -50 to be x
we have the other two angles as,
180-(-50) = 180+50 = 230
360+(-50) = 360-50 = 310
:D hope that helps, not specifically for this question, but in general.
--- End quote ---
Ohh cool !! hadta read it thrice tho but i get it.. Thanks .. :)
Fastal:
can we look at my questions now :)
i made it easier by doing the previous bits---see attached pictures
img010 is for 2(d)(iii) from 2005 november p4
3(a)(iv) is from 2005 june p4
Ghost Of Highbury:
--- Quote from: @d!_†oX!© on May 08, 2010, 06:43:30 pm ---I know you got this already, but i don't mind elaborating :P
90
S | A
180----------0/360
T | C
270
Read the above as follows before starting:
1) A=All +ve , S= Sin +ve , T=Tan +ve , C=Cos +ve
2) This shows the four quadrants, going anticlockwise from 0 to 90 to 180 270 to 360.
3) This means that any angle in a specific quadrant is +ve acc to 1)
So, now coming to your question, the question is talking about sin, which is +ve in the 1st and 2nd quadrant.
The angle already given to us is in the 1st quadrant, so now we know we will get the same value in the second quadrant in the 2nd quadrant (180-x) or the after 360 (360+x)
Taking -50 to be x
we have the other two angles as,
180-(-50) = 180+50 = 230
360+(-50) = 360-50 = 310
:D hope that helps, not specifically for this question, but in general.
--- End quote ---
lol, gr8 u did, i was pretty bored to type it..By the way
just to add something here..v had a mnemonic to remember the All Sine tan cos.
its All silver tea cups.
all , sine cos tan. :D
Ghost Of Highbury:
--- Quote from: Fastal on May 08, 2010, 07:16:51 pm ---can we look at my questions now :)
i made it easier by doing the previous bits---see attached pictures
img010 is for 2(d)(iii) from 2005 november p4
3(a)(iv) is from 2005 june p4
--- End quote ---
sorry for the late reply.
heres 2)d)iii
work out the inverse first.
determinant - 1.5
(1/1.5 0 ) = (2/3 0)
( 0 1.5/1.5) (0 1)
now first, u have to learn this list of matrix transformations, dont learn them all, learn the imp. ones like shear , stretch, enlargement etc, heres it : https://studentforums.biz/index.php/topic,5575.msg167872.html#msg167872 (3rd post)
and this is what it says abt stretch
Stretch
1. x invariant wer k=scale factor (1 0)
(0 k)
2. y invariant wer k=scale factor (k 0)
(0 1)
now if u notice, out matrix is like the 2. one.
therefore, it means, that its stretch with y invariant and scale factor = k = 2/3
and abt the shear question, sry, im a little confused myself. will try to help asap/
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