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Mathematics: Post your doubts here!

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Can someone help me?


Find the cartesian equations of the plane through (--1,1,2) and (2,0,-1) perpendicular to the plane x+y-2z=1.



use the two points to obtain a direrction vector in the plane....and usee the given plane equation's normal as another vector in the required plane....cross these two vectors and there u go ....


Can someone please write it? I'm still stuck. What does 'cross these vectors' mean please?
 
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how to get my self done wd p3 .. :S :(
aoa wr wb!
solve one paper ...try recent ones..check ur paper from the mark scheme and mark yourself....now make out which topics you werent really sure..revise them thoroughly...
go through your notes for all chapters...solve few more papers....mark urself..if you feel u r unsure about something revise that chapter again ;)
 
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32
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Can someone help me?


Find the cartesian equations of the plane through (--1,1,2) and (2,0,-1) perpendicular to the plane x+y-2z=1.



use the two points to obtain a direrction vector in the plane....and usee the given plane equation's normal as another vector in the required plane....cross these two vectors and there u go ....


Can someone please write it? I'm still stuck. What does 'cross these vectors' mean please?
 
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Why did you reach to this?
This is not an equation, it is an inequality! :p

25cos(θ - 73.74) = 15
Simply solve this but remember the range is negative also so also take the value of negative (360 - x) in the 4th quadrant
 
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Thanks for replying!
when you make X the subject does the answer you get have to be within the new range or the one specified in the question?

I get (2X-71.57)= 50.77 and 2x-71.57=(360-50.77)

2X=122.3 and 2X=380.8
X=61.2 X=190.4
in 2nd quadrant, only sin is +ve
then, do 360-190.4=169.6
then, 180-169.6=10.4

final answer should be in range specified in the question
why is it "360-50.7"
I dont undestand this part
"in 2nd quadrant, only sin is +ve
then, do 360-190.4=169.6
then, 180-169.6=10.4"
 
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i had the same problem
what i did first was to make lny the subject ---> lny=(2x+1)/x
now differentiate each side ------> lny becomes 1/y (dy/dx)
differentiate (2x+1)/x using quotient rule ------- [2x-(2x+1)]/x^2 = -1/x^2
therefore------- 1/y (dy/dx)= -1/x^2,
take 1/y to the other side becomes ------− - y/x^2

Well !! That's the only way left to solve this question .. Nyz thanks :)
 
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