Exam 1 Flashcards
where are octants situated (R2 or R3)
R3
how to find the angle between vectors
cos-1 (u*v)/(|u||v|)
what are skewed lines
not parallel and they do not intersect
positive orientation
gotten by letting t increase from a to b
defualt orientation of line if not specified
put arrow going counter-clockwise
what vector is perpendicular to all other vectors
0 vector
when is torque at max
when sin =1 so angle is pie/2
when angle is pie/2, r and F are perpendicular
what does |u|cos equal
(u*v)/ |v|
dot product of u and v divided by magnitude of v
what is the absolute value of a vector mean
the length of U (magnitude of U) (norm of U)
normal vector
a vector that is perpendicular to the plane
what is parallel to a vector
the vector multipled by a scallar
V || KV
what does it mean when K is greater than/equal to 0
vector whose direction is that of u and whose magnitude is K(U) (magnitude of u)
what to do when UxV are not parallel
draw parallelogram, find area of parallelogram (drop right angle); get |v||u|sin
when does the point hit the line
when the distance from point Q to line L is less than the two radians combined
how to find the distance between points
draw a right triangle, draw another one, use pythag theorem
the first line down is (z-c)
the next line down (second triangle) is (x-a)
the horizonta line (connecting 2nd trinagle to og point) is (y-b)
The points are (a,b,c) and (x,y,z)
line down in first triangle goes to (x,y,c)
the next line down leads to (a,y,c)
properties of cross products
UxV= -(VxU)
|UxV|= |v|u|sin
(au) x (bv)= (ab)(UxV)
Ux(v+w)= (UxW)+(VxW)
Cross product
UxV
how are projvU and scalvU related
|projvU| = |scalvU|
how to find the direction of a vector
u/|u| = (1/|u|)(u)
opposite direction is making it negative
when is line parallel to vector
P.P ||v
P.P=tv for some scalar t
sphere
center (a,b,c) and radius r
(a,b,c) any real number, r is greater than 0
(x-a)^2 +…….= r^2
completing the square
how to move from R2 to R3
<x,y>
R3 is <x,y,z>
so R3 is <x,y,0>
YZ plane
x=0
goes down, right, sky without stopping
how to find points where origin intersects the coordinate axes
find the intercepts for x,y,z
set the other two to 0 in equation and solve)
(v/|v|)
<cos, sin>
if not on origin <a+cos, b+sin>
coordinate notation
<x,y>
what is scalvU
scalar component of u in dir of v
|u|cos
projvU
orthogonal direction of U onto V
how much of u points in direction of v
how many answers are there to what is perpendicular to u and v
infinitely many because scalars are involved
k(UxV)
how to find area of triangle
make a parallelogram
triangle OQP
.5(area of parallelogram)= .5 (|OP x OQ|)
combine OP and OQ
then do matrix for the cross product
then multiply by .5
Identities with scalars and vectors
U,V,W are vectors; K,L are scalars
U+V=V+U
(U+V)+W=U+(V+W)= U+V+W
U+0=U=0+U
U+-U=0=U-U
K(LV)=(KL)U
K(U+V)=KU+KV
(K+L)U=KU+LU
1U=U
0U=0
K0=0
what is torque
when force F is applied at tip of r
creates a TWISTING motion at origin
angle is N*m
when giving equation for line what is t
0<t<1
what is area of parallelogram
|v||u|sin
the area of parallelogram is wqual to the magnitude of the cross product |Uxv|
How are vectors represented
an arrow
has direction (way its pointing)
the length is magnitude of vector
how to find a line through a point (P.= x.,y.,z.) that is perpendiclar to the vector <a,b,c,>
P(x,y,z) any point on l
OP= OP. +OP
4 different equations one can use:
<x,y,z>= <x.,y.,z.> + tv
r= r. +tv
<x,y,z>= <x.,y.,z.> + t(a,b,c)
<x,y,z>= (x.t+at, y.t+bt, z.+ct)
what happens when different planes have the same normal vector
the planes are parallel
parallel planes
n1 and n2 are parallel
n1||n2
what does U+V mean, U-V, KU
<u1+v1; u2+v2; u3+v3>
<u1-v1; u2-v2; u3-v3>
<Ku1, Ku2, Ku3>
how many equations are there for one line
infinitely many
when is torque the largest
when r and F are perpendicular
example of vectors
acceleration, force, velocity
how to find the distance of a point to a line
|PQxV|= |v|d
d= (|PQxV|)/|V|
angle is (d)/(PQ)= sin
what is a degenerate case
when k=0
the 0 scalar is parallel to any vector
(the direction is also the same)
what happens when one vector is 0 in a cross product
the cross product will equal 0