2004 paper 2 Q6b

x_Jo_x

Posted 13 May 2007 - 04:25 PM

i managed to get all the way down to getting x= 105.7 and 372.3

But why would you take off 360 at the end to get the answer 12.3? i just don't get it, is there a rule or am i just being stupid?

babeasc

Posted 13 May 2007 - 04:35 PM

You need to take off the 360 because it asks for values of x between 0 and 90.
Since the answers you get are above that range, then the values of x wanted in the answer must occur in the previous cycle.

since 105.7 - 360 is not between 0 and 90 (-254.3), it can be discounted.
Final answer = 372.3 - 360 = 12.3 [only answer that lies withing range]

x_Jo_x

Posted 13 May 2007 - 04:38 PM

Thank you very much!

Azie

Posted 13 May 2007 - 04:47 PM

i managed to get up 2 the point where x - 59 = 46.7, an im guessin to get the 105.7, u do 59 + 46.7, but how do u get the 372.3 answer?

xClairex

Posted 13 May 2007 - 05:14 PM

2cosx + 5 sinx =√34 coz (x-59) = 4
cos (x-59) = 4/√34
(x-59)= cos^-1 (4/√34) = 46.7 and 313.3
x= 46.7 +59 = 105.7 and 313.3 + 59 = 372.3

372.3 - 360 = 12.3

x= 12.3 as its within the limit

Azie

Posted 13 May 2007 - 05:18 PM

thanks a lot xClairex

Posted 13 May 2007 - 05:43 PM

thanks a lot no problem glad it helped  