• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Mathematics: Post your doubts here!

Messages
128
Reaction score
112
Points
53
O5SAvjD.png


Could someone please help me with part (iii) of the question? Its kinda urgent
The answer to part(ii) is √20sin(theta + 63.43)
Thanks
 
Messages
96
Reaction score
221
Points
33
Thanks a lot for your help.. but the answer to the question is 74.4 and 338.7 :(
yeah
subtract 63.43 from both values
check I have written 137.9 and 402.1 is equal to (Theta+ 63.43) not Theta
so for theta you have to subtract 63.43 from both sides
the last line didn't come in the pic where I subtracted :oops:
It was my careless mistake when I took the snap :oops:
 
Messages
128
Reaction score
112
Points
53
yeah
subtract 63.43 from both values
check I have written 137.9 and 402.1 is equal to (Theta+ 63.43) not Theta
so for theta you have to subtract 63.43 from both sides
the last line didn't come in the pic where I subtracted :oops:
It was my careless mistake when I took the snap :oops:
Oh thats not a problem, dnt worry :)
I didnt get one part of the solution you posted.
theta + 63.43 = (inv)sin(3/√20)
hence, theta + 63.43 = 42.13
theta = -21.3

How did you get your values?

Sorry for bothering.. I'm a li'l weak in trigonometry
 
Messages
1,394
Reaction score
1,377
Points
173
i am out of form B| ask daredevil :p. stupid computing project took me 8 sleepless nights. btw where the hell were you :p. I thought we would get to the magic no (100) in the convo without you :p
hahaha.... i am here to agree to that syed1995 :p

and yeahhh where were u??! the century is not something u want to miss dear sir ... esp not in the T-20 season :p it's important!:p
 
Messages
1,824
Reaction score
949
Points
123
hahaha.... i am here to agree to that syed1995 :p

and yeahhh where were u??! the century is not something u want to miss dear sir ... esp not in the T-20 season :p it's important!:p

i was waiting for you guys to reach 99 to make an entry and bowl you guys down.. but you guys slowed down :(

anyways on topic, answer that question DEAR!
 
Messages
96
Reaction score
221
Points
33
Oh thats not a problem, dnt worry :)
I didnt get one part of the solution you posted.
theta + 63.43 = (inv)sin(3/√20)
hence, theta + 63.43 = 42.13
theta = -21.3

How did you get your values?

Sorry for bothering.. I'm a li'l weak in trigonometry
Naah don't be sorry
these are the few twists in trigonometry which I think is literally pointless!
you see what you wrote is logically right! but we have a range given for theta.
Now sine ratio is +ve in 1st and 2nd quadrant.
we have a range given for Theta but we have value for sin(theta + 63.43)
we can't simply take sin inverse and subtract 63.43 from the angle as on both sides our variable isn't the same.
I'll make it bit more simple
consider Theta+63.43= Y
and you have sinY = 3/√20
but your given range is for Theta not Y
so convert Theta to Y
I have shown in the picture
63.43 < Y < 423.43
Now back to the solution you suggested
yes you are right! sin inverse of 3/√20 does equal to 42.13
but that's out of the given range of Y
that's why 42.13 is not acceptable
quick tip- when solving trig sums where range is not 0<variable used for angle<360 it's better if you draw the range cycle and mark out possible quadrants your angle could lie in (here since my sine ratio is +ve I have marked 1st and 2nd quadrant)
and when writing an answer make sure you mention ALL THE POSSIBLE VALUES thus I got 2 values

guess I wrote too long but you said you were weak in trig so I tried to explain it as clearly possible!
:)
 

Attachments

  • 20140324_195602.jpg
    20140324_195602.jpg
    1.4 MB · Views: 5
Last edited:
Messages
302
Reaction score
432
Points
28
Solve the inequality I x I < I 5 + 2x I
I got two values to x as -5 and -5/3 and they are right ,
but how to make the inequalities finally ..

someone already solved it , but can anyone give alternative way ? of finding the range of values of x ??
 
Messages
1,983
Reaction score
3,044
Points
273
Solve the inequality I x I < I 5 + 2x I
I got two values to x as -5 and -5/3 and they are right ,
but how to make the inequalities finally ..

someone already solved it , but can anyone give alternative way ? of finding the range of values of x ??
Do yourself a favour. Watch these three videos:
http://examsolutions.net/maths-revi...functions/modulus/inequalities/tutorial-1.php
http://examsolutions.net/maths-revi...functions/modulus/inequalities/tutorial-2.php
http://examsolutions.net/maths-revi...functions/modulus/inequalities/tutorial-3.php
If there's some problem like youtube is blocked i know you will figure out a way to see these videos.
 
Messages
96
Reaction score
221
Points
33
Solve the inequality I x I < I 5 + 2x I
I got two values to x as -5 and -5/3 and they are right ,
but how to make the inequalities finally ..

someone already solved it , but can anyone give alternative way ? of finding the range of values of x ??

At first I got it in the form of a^2 - b^2
then simplified it
about how I got the three possible ranges on the table,
if it was an equation instead of inequality then x = -5 and -5/3
if drawn on a number line there are 3 possibilities of the correct range
so draw a table
you get the signs for (x + 5) by checking in each range if a value of x is substituted what result you get
for example in the range x< -5 , take a value less than -5
If we take -6 then (-6 +5) = -1 which is negative (thus the minus sign in the table for x+5 in the x<-5 coloumn )
so (x+5) is -ve when x< -5
check with the rest range possibilities
for (3x + 5) do the same thing
(x+5) is multiplied to (3x+5)
so multiply the corresponding signs
example (x+5)(3x+5) for x<-5 = -ve multiplied by -ve = +ve
My initial inequality was (x+5)(3x+5) > 0
that means the product should be +ve
from the table this happens only when x<-5 or x>-5/3
 

Attachments

  • 20140324_225826.jpg
    20140324_225826.jpg
    1.4 MB · Views: 3
Messages
128
Reaction score
112
Points
53
Naah don't be sorry
this are the few twists in trigonometry which I think is literally pointless!
you see what you wrote is logically right! but we have a range given for theta.
Now sine ratio is +ve in 1st and 2nd quadrant.
we have a range given for Theta
but we have value for sin(theta + 63.43)
we can't simply take sin inverse and subtract 63.43 from the angle as on both sides our ariable isn't the same.
I'll make it bit more simple
consider Theta+63.43= Y
and you have sinY = 3/√20
but your given range is for Theta not Y
so convert Theta to Y
I have shown in the picture
63.43 < Y < 423.43
Now back to the solution you suggested
yes you are right! sin inverse of 3/√20 does equal to 42.13
but that's out of the given range of Y
that's why 42.13 is not acceptable
quick tip- when solving trig sums where range is not 0<variable used for angle<360 it's better if you draw the range cycle and mark out possible quadrants your angle could lie in (here since my sine ratio is +ve I have marked 1st and 2nd quadrant)
and when writing an answer make sure you mention ALL THE POSSIBLE VALUES thus I got 2 values

guess I wrote too long but you said you were weak in trig so I tried to explain it as clearly possible!
:)
Thanks a lot for the great explanation. Appreciate it..
 
Messages
302
Reaction score
432
Points
28
Messages
5
Reaction score
5
Points
11
Please somebody explain how it is solved with its steps...many thanks
O/n 2013 9709 question 6
 

Attachments

  • Screenshot_2014-03-26-02-14-02-1.png
    Screenshot_2014-03-26-02-14-02-1.png
    71.6 KB · Views: 14
Top