P3 Vector q Watch

This discussion is closed.
toxi
Badges: 0
#1
Report Thread starter 14 years ago
#1
from heinemann p3 book, p. 188 q 41

r= λi + (2λ-1)j-k
s= (1- λ ) i + 3λ j + (4λ-1)k
(a) find the values of λ for which r & s are perpendicular
when λ=2 r & s are the position vectors of the points A & B respectively.

b. Find AB

c. Use a scalar product to find the size of <BAO
0
m:)ckel
Badges: 2
Rep:
?
#2
Report 14 years ago
#2
(Original post by toxi)
from heinemann p3 book, p. 188 q 41

r= λi + (2λ-1)j-k
s= (1- λ ) i + 3λ j + (4λ-1)k
(a) find the values of λ for which r & s are perpendicular
when λ=2 r & s are the position vectors of the points A & B respectively.

b. Find AB

c. Use a scalar product to find the size of <BAO
(a) use dot product: λ(1- λ ) + (2λ-1)*(3λ) -1(4λ-1) = 0
now expand, simplify and solve the quadratic to get the possible values of 'λ'

(b) sub λ=2, to get A=2i + 3j - k, and B= -i + 6j + 7k
vector AB = B - A = -3i + 3j + 8k

(c) find the modulus of vecor AB, the modulus of vecor AO, and use the dot product formula:
AB . AO = |AB|.|AO|[email protected] ,where @ is the angle you want to find
0
kikzen
Badges: 14
Rep:
?
#3
Report 14 years ago
#3
damnyou mockel!
0
m:)ckel
Badges: 2
Rep:
?
#4
Report 14 years ago
#4
(Original post by mockel)
(a) use dot product: λ(1- λ ) + (2λ-1)*(3λ) -1(4λ-1) = 0
why does this come up? just to make it clear, the middle part says (2λ-1)* (3lamda)
0
toxi
Badges: 0
#5
Report Thread starter 14 years ago
#5
thanks..
0
Fermat
Badges: 8
Rep:
?
#6
Report 14 years ago
#6
(Original post by mockel)
why does this come up? just to make it clear, the middle part says (2λ-1)* (3lamda)
It comes up because you haven't clicked the checkbox to disable smilies in that post :)
So, when you want lambda, and put &#955 ; (with no space before the ; ) and that is immediately followed by a ')', then it's interpreted as a smilie, viz. ;)
Disable smilies for a post and it'll come up ok.
0
X
new posts
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • University of the Arts London
    MA Performance Design and Practice Open Day Postgraduate
    Thu, 24 Jan '19
  • Brunel University London
    Undergraduate Experience Days Undergraduate
    Sat, 26 Jan '19
  • SOAS University of London
    Postgraduate Open Day Postgraduate
    Sat, 26 Jan '19

Are you chained to your phone?

Yes (74)
19.32%
Yes, but I'm trying to cut back (155)
40.47%
Nope, not that interesting (154)
40.21%

Watched Threads

View All