How do I parametrize a line integral with vector functions?

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To parametrize a line integral with vector functions, it's essential to express the vector field F in terms of the parameter t, ensuring that the points (x, y) lie on the curve defined by r(t). The integration should only consider values of x and y that correspond to the curve, which is determined by the parametrization. The user initially struggled with the concept but eventually resolved the issue independently. Understanding the relationship between the curve and the vector field is crucial for proper integration. The discussion highlights the importance of parametrization in evaluating line integrals effectively.
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(disregard the [5+5+5] in the question)attempt:
dr=(et(cost)+(sint)et)\hat{i} + (-et(sint)+(cost)et)\hat{j}

∫<3+2xy, x2-3y2>\cdot<et(cost)+(sint)et, -et(sint)+(cost)et>dt

..at which point i remembered i had to parametrize F in terms of t, but didn't know how to do
 
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you want to integrate only over those values of x and y that lie on the curve mapped out by r(t) ... so what determines if a point (x,y) is on r?
 
to answer your question, it would be if curve C lies if the domain of F, i don't see how this would help me though, I'm trying to put the vector field in terms of t.
 
you want to integrate only over those values of x and y that lie on the curve mapped out by r(t)

i would have to put the curve that is in terms of t, into some function of x and y then, how?
 
this was a stupid question. Sorry, i just figured it out...
 
Well done :)
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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