Qualification > Math
[CIE] All Pure Mathematics (P1, P2 and P3) doubts here !
ashwinkandel:
Thanks Arthur Bon Zavi .... Your help is really appreciated :)
Alpha:
Tuitions over, so I'll post my doubt here.
http://www.xtremepapers.com/CIE/International%20A%20And%20AS%20Level/9709%20-%20Mathematics/9709_s11_qp_31.pdf
No 3, on vectors.
Points A and B have coordinates (-1, 2, 5) and (2, -2, 11) respectively. The plane p passes through
B and is perpendicular to AB.
(i) Find an equation of p, giving your answer in the form ax + by + cz = d. [3]
(ii) Find the acute angle between p and the y-axis. [4]
How would you proceed with the second part?
I got the answer, but I checked the markscheme, and don't understand the procedures there.
astarmathsandphysics:
The question is the same as finding the angle between (a,b,c) and (0,1,0)
Alpha:
--- Quote from: astarmathsandphysics on October 14, 2011, 02:54:06 pm ---The question is the same as finding the angle between (a,b,c) and (0,1,0)
--- End quote ---
What will you take as (a,b,c)?
I took two points on the y-axis.
I cannot understand why Cambridge has taken vectors OB and OA. Shed some light please? :-\
Deadly_king:
--- Quote from: ~Alpha on October 14, 2011, 03:01:27 pm ---What will you take as (a,b,c)?
I took two points on the y-axis.
I cannot understand why Cambridge has taken vectors OB and OA. Shed some light please? :-\
--- End quote ---
I don't think I'll be of much help since I've forgotten most of my Maths by now :-\
Anyway I'll try as much as I remember though am not so sure.....
To find the angle between a line and a plane we first have to find the angle between the normal of the plane and the direction vector of the line.
We need to find the direction vector of the normal of the plane by using OA and OB -----> OB - OA
Then you use the formula to find angle ;)
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