A community for students.
Here's the question you clicked on:
 0 viewing
TrojanPoem
 one year ago
Mechanics
TrojanPoem
 one year ago
Mechanics

This Question is Closed

Jack1
 one year ago
Best ResponseYou've already chosen the best response.0what specifically about mechanics? do u have an engineering based question?

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Nah, general question.

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Are you an engineer ?

phi
 one year ago
Best ResponseYou've already chosen the best response.1if we use the Law of Cosines on that triangle dw:1444139454924:dw

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0That's why I was getting the wrong angles ,

phi
 one year ago
Best ResponseYou've already chosen the best response.1x is the angle between u and v but in the triangle the "opposite angle" is 180  x cos (180x) =  cos(x)

phi
 one year ago
Best ResponseYou've already chosen the best response.1a picture drawn to scale is very helpful. (If done very accurately, you can measure the answer), but even a rough drawing gives a good estimate of the answer (i.e. angle and length of the vector)

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0How ? It wasn't clear 131 ? on the last question

phi
 one year ago
Best ResponseYou've already chosen the best response.1Using the Law of Cosines idea? dw:1444139889064:dw

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0dw:1444139666557:dw

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Why isn't 180  Alpha = alpha ? Symmetry

phi
 one year ago
Best ResponseYou've already chosen the best response.1alpha (apparently, based on the answer choices) is the angle between v and f the angle between u and v is alpha + theta

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0dw:1444140291240:dw

phi
 one year ago
Best ResponseYou've already chosen the best response.1yes. with theta= 40, you get 120alpha now it will work

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0300/ sin alpha = 256.9 / sin40 sinalpha^1 = 48.64 ,

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0What am I doing wrong ?

phi
 one year ago
Best ResponseYou've already chosen the best response.1I think it would help if you drew a picture that more closely matched the situation

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0dw:1444140790074:dw That's our start then dw:1444140826725:dw then using the sine rule.

phi
 one year ago
Best ResponseYou've already chosen the best response.1as you know the Law of Sines is ambiguous when you have an obtuse angle notice sin(131.4)= sin(48.6) In this problem, you have to recognize you should choose the 131.4

phi
 one year ago
Best ResponseYou've already chosen the best response.1V almost doubles back on u, and we have an obtuse angle opposite the longest side = 300 Considering these subtleties, perhaps using components (of vectors) is more straightforward

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Using vectors'd give me the answer directly, however, I've to answer this question using cosine / sine rule :/

phi
 one year ago
Best ResponseYou've already chosen the best response.1the other way around the ambiguity is choose the acute angle rather than alpha

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Alpha doesn't seem like an obtuse in the drawing :/

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Fine, thanks phi :)

phi
 one year ago
Best ResponseYou've already chosen the best response.1\[ \frac{\sin (140\alpha)}{60}= \frac{\sin(40)}{256.9}\]

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Phi, I noticed that 256.9 is out of the choices ,

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0a)112.7 b ) 145.9 c) 154.3 d ) 257.9

phi
 one year ago
Best ResponseYou've already chosen the best response.1Yes, I noticed that before. I assume it is a typo. Here are the 3 vectors

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Ok, as you're sure.

phi
 one year ago
Best ResponseYou've already chosen the best response.1You can ask your teacher, but the numbers work out to 256.9

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0Yeah, 257.9 works too with 131.4

TrojanPoem
 one year ago
Best ResponseYou've already chosen the best response.0u+v= f so v= fu f=<300,0> (we let f point along the xaxis u= 60<cos 40, sin 40> v= <60 cos(40)  300, 60 sin(40) > now find the magnitude and angle of v v = 256.9 angle = atan(y/x) = 8.6 deg in the 3rd quadrant= 171.4 alpha = 171.440= 131.4 deg maybe it's a typo we've two solutions here which come with the same result.

phi
 one year ago
Best ResponseYou've already chosen the best response.1Yes, I'm sure the magnitude is 256.9 But complain to your teacher.
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.