2210-90 Exam 1
Fall 2013
/
Name
Show all work and include appropriate explanations when space is provided.
Instructions.
answers unaccompanied by work may not receive full credit. Please circle your final answers.
1. (l0pts) Consider the vectors u
=
(1.5,—i) and v
Correct
(4,1,1). Find
(a) (2pts) v + 3u
>
1
q,i,
(b) (2pts) Iu
tU
(c) (3pts) u v
3
(iq)
-i-(c)(’+ (—0(i)
(d) (3pts) u x v
fri
(i
ç
4
-
1
2. (7pts) Find a unit vector that is orthogonal to the plane containing the points P
(2,0,1), and R= (0,0,5).
=
(1, 1, —1),
Q
=
—
)
-If_l1)
)— (tt-i>
<0
c
o
= 1
I
/
—1
j
1-1
-I
I
.
‘1z))
—
3. (6pts) The following equation determines a sphere. Find the center and radius of the sphere. Hint:
Complete the squares.
9
x 2 ±y++2x—6y=—6
Center=
(1,
Radius=
(
—l
1
,
3
,
0
(+
)*
ii
—
L-y)
(
1
3
(xi)(
1
2-3
4. (6pts) Find a vector equation for a line that passes through the point (1, 2, 3) at t
(—1,4,—2) at t = 1. Note, your answer should be a curve
r(t)
=
=
0 and the point
(x(t),y(t),z(t))
ic
-l-t)-i,3>+
1 3-5t>
12t)2+2t
z,-c>
1
t2-
5. (l6pts) Suppose a particle’s position at time t is given by the curve
5ti + sin (3t)j
r(t)
—
cos (3t)k.
2 x + cos
2x
For this problem, it may be helpful if you remember the trig identity sin
=
1.
(a) (3pts) Find the velocity v(t) of the particle at time t.
3
3ۍ(3t)3
i-
3si
(b) (3pts) Find the acceleration a(t) of the particle at time t.
3
&t —stu(3t)j-Ftos(3t)fr-
Ift
(c) (3pts) Find the arc length of the curve between times t
tt5 4c ;:;;
[si tt II.
3
L--
r
3
iiv lk)l)
—
—
r-LIi
(e) (4pts) Find the curvature
—I
J—
/
[0
t(t)
4
=
0 and t
=
3.
3
u
0
(d) (3pts) Find the unit tangent vector T(t)
=
v(t)
IIv(t)IV
ct3cos()fr?st[3),)
HT’(t)II of the particle’s path at time t.
11vtI
-I(3t) (3t)
2
6. (2lpts, 1.5pts each) Match the equation with the type of surface it determines by writing the appro
priate capital letter (A-I) in the provided blank. The last six equations are written in cylindrical or
spherical coordinates. Some letters may be used more than once.
9
9
x- + y
A
I3
1,
9
X
9
+4
9
—
B Ellipsoid
—Y=l
2 +y
x
2 +
2
A Elliptic Paraboloid
1
z
=
C Hyperboloid of one sheet
1
2
2
D Hyperboloid of two sheets
x —2y —z =1
9
z
&
=
9
x-
9
E Hyperbolic Paraboloid
—
9
9
x- + y- + zx
‘4
=
—
9
9
2
.2
x + yr
=
F Plane
1
G Sphere
z
H Cylinder
1
=
I Cone
=
r=1
3
I
&
2r 2 +z 2 =1
7r
Y
5
2
p=
F
pcos
=
1
7. (9pts) Convert between Cartesian, cylindrical, and spherical coordinates as indicated. Please simplify
as much as possible.
(a) Find the spherical coordinates of the point with Cartesian coordinates (—1, 1,
4
37r/
2—
1L
k2± t*ii’)
(b) Find the cylindrical coordinates of the point with Cartesian coordinates (1,
9=
—2)
-7__
--
4—
173
(c) Find the Cartesian coordinates of the point with spherical coordinates (4,
()
I
=
1
()s)
I.. 2-/i 2-)
3
,)
=
Ll-L
1
T(
-
8. (l2pts) Evaluate the following limits. If they do
(a)
urn
(x,y)(O,O)
)
2
cos(x
i
I
toS(0)
—
—
‘DNE’ and explain why.
riot exist, write
2
y
I
—
4
(b)
lirn
(x.y)—*(O.O)
x + 2y
X
p
(o t.Ij -(S (o)i t-<.i
—
+
lII.4.k
)-(VgO
1
(
1
Li
!..±_J
1o
to
)-(u
(x
u
1
(c)
lirn
(xy)—(OO)
—y
2 + y
X
2
0 )
X-
x-j
‘j
‘
—z
---
Hint: Use polar coordinates.
i&
(—J)
r
‘
o
cD
—
iit9
°°
h
9. (l3pts) Consider the function
=
2
sin (xy)
—
x.
(a) (7pts) Find the equation of the tangent plane to the graph of
sy)
cy)
=
f(x, y)
at the point (1,0, —1).
l.
ftiio)
fx
z
2x
SIH
Ixy)
cs(xy)
3
X
co
+
Ocy)
I
(1, o)
— .fcitô)
-x#y
(b) (6pts) Find the following second derivatives:
Z
.
f(x,y)=
ZsaLxy)
+vq ‘/xytc(fy) —xyii-(xy)
ii. f(x,y)=
iii. f(xy)=
toS(xy) _x
1
X
5
3
(xy)
4
-5.