# line integral helps

• Jul 10th 2013, 12:13 AM
n22
line integral helps
Hello,
I would very much appreciate help with this .I just dont get it .(and Im not supposed to use greens theorem)thanks.just the normal line integral.
(2x − y + 4)dx + (5y + 3x − 6)dy around a triangle in the xy-plane
with vertices at (0, 0), (3, 0), (3, 2), traversed in the anti-clockwise direction..
• Jul 10th 2013, 02:45 AM
Prove It
Re: line integral helps
Can you parameterise each of the segments that make up the triangle?
• Jul 11th 2013, 04:08 AM
n22
Re: line integral helps
Quote:

Originally Posted by Prove It
Can you parameterise each of the segments that make up the triangle?

Hello!

AB has coordinates (0,0) and (3,0)-->parametrization is x=3t

BC has coordinates (3,0) and (3,2)-->parametrization x=3+3t,y=2t
CO has coordinates (3,2) and (0,0)-->parametrization ,x=3;y=2
• Jul 11th 2013, 05:40 AM
Prove It
Re: line integral helps
Quote:

Originally Posted by n22
Hello!

AB has coordinates (0,0) and (3,0)-->parametrization is x=3t What about the y parameterisation?

BC has coordinates (3,0) and (3,2)-->parametrization x=3+3t,y=2t x is constant, why have you parameterised it to change?
CO has coordinates (3,2) and (0,0)-->parametrization ,x=3;y=2 Why do you have x and y as constants when they clearly change?

The only one I agree with is your x parameterisation for AB and your y parameterisation for BC. I also assume that the third segment should be CA, not CO.

Also, use a different parameter for each segment.
• Jul 11th 2013, 02:42 PM
n22
Re: line integral helps
Quote:

Originally Posted by Prove It
The only one I agree with is your x parameterisation for AB and your y parameterisation for BC. I also assume that the third segment should be CA, not CO.

Also, use a different parameter for each segment.