This preview shows pages 1–2. Sign up to view the full content.
Math 10C (Overholser)
Quiz 3
Oct. 29, 2010
Name:
TA:
Section # or Time:
Instructions: You may use a calculator but must show all steps needed to derive your answer. Answers
with no work shown will receive no credit. No simpliﬁcation of solutions is required for full credit: you may
leave expressions such as sin(4) or
1
√
2
as they are.
1. (5 points) A helicopter is ﬂying at an airspeed of 400 km/hr. A cross wind is blowing
from
the southeast
at 30 km/hr. What direction should the helicopter head to
end up
going directly south? You may ﬁnd
it helpful to recall that a unit vector at an angle of
θ
from the xaxis is given by cos
θ
~
i
+sin
θ
~
j
. You may
give your answer in terms of either an angle or a unit vector pointed in the appropriate direction.
Solution:
Let
~w
be the velocity vector of the wind. Since the wind is going towards the northwest, an angle
of 135
◦
from the xaxis, at 30 km/hr,
~w
= 30 cos 135
◦
~
i
+ 30 sin 135
◦
~
j
.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
 Spring '10
 rosanna

Click to edit the document details