Solved

Algebra. How to solve with two missing variables?

Posted on 2011-03-24
6
459 Views
Last Modified: 2012-05-11
If you skip to the very bottom of this force problem you find two equations. In a rectangle called step (2) it says; Sub in T3 in symbols; Solve for T2.

The circled variables are unknowns.

How do I solve this when both T2 and T3 are unknowns? By the way, T1 is 25.
This is as far as I get. Thanks.

T2 sin40  +  T3 sin30 =T1
                    T2 sin40 =T1 -  T3 sin30  
                    T2 sin40 =25 -  T3 sin30          


twoD-forces02.jpg
0
Comment
Question by:kadin
  • 3
  • 2
6 Comments
 
LVL 27

Assisted Solution

by:aburr
aburr earned 334 total points
ID: 35212830
in x component eq solve for T3

T3 = T2 cos 40/cos30

in y component eq put the above eq in place of T3

T2sin40 - T2 cos 40/cos30 = T1
remember that T1 = 24 N (start of prob). Now the only unknown is T2  - solve
put the T2 in the x eq to get T3

QED

Note that the procedured here is exactly like the solution given you before.
Solve for separate one variable and substitute into the other equations. Repeat if necessary
0
 

Author Comment

by:kadin
ID: 35212851
Thanks. I will need some time to study what you said.
0
 

Author Comment

by:kadin
ID: 35213100
Thanks for your help. I see where I misread the equation. I thought T3  cos30 was one unit when it's actually T3(cos30). Multiply the two. There for I can divide cos30 to the right side thus isolating T3.

My next challenge is how to solve for T2 when there are two T2's in the same equation. How do I isolate two of them?

T2sin40 - T2 cos40/cos30 = T1

Let say I had a simpler equation.

T2(4) - T2(6)/2=24
0
Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

 
LVL 84

Assisted Solution

by:ozo
ozo earned 166 total points
ID: 35213986
T2(4) - T2(6)/2 = T2((4) - (6)/2)
0
 
LVL 27

Accepted Solution

by:
aburr earned 334 total points
ID: 35216067
"T2sin40 - T2 cos40/cos30 = T1"

notice that there is a T2 in both terms on the left. Factor the T@ out

T2(sin40 - cos49/cos30) = T1   that is the same a aT2   divide both sides by a
you get
T2 = T1/(sin 40 - cos40/cos30)
There you have it
I would recommend that you review your simple algebraic operations.
0
 

Author Closing Comment

by:kadin
ID: 35217878
Thanks. I will work on the rest of this and see if I can get the right answer.
0

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
CAGR Calculation For SIP 13 83
Error in calculation 2 79
coolers to wear for eyes in workplace (8-10 hours of computer starring!) 10 105
Two Dice Roll Probabilities 3 69
We are taking giant steps in technological advances in the field of wireless telephony. At just 10 years since the advent of smartphones, it is crucial to examine the benefits and disadvantages that have been report to us.
Article by: Nicole
This is a research brief on the potential colonization of humans on Mars.
This is a video describing the growing solar energy use in Utah. This is a topic that greatly interests me and so I decided to produce a video about it.
Finds all prime numbers in a range requested and places them in a public primes() array. I've demostrated a template size of 30 (2 * 3 * 5) but larger templates can be built such 210  (2 * 3 * 5 * 7) or 2310  (2 * 3 * 5 * 7 * 11). The larger templa‚Ķ

860 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question