# Tagged Questions

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### double integral over an arbitrary triangle

Assume we have an arbitrary triangle ABC in x-y plane and we want to integrate a function $f(x,y)$ over surface of this triangle as shown in fig. 1: We can define another coordination system [x' ...
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### Solving integral including a triangle

How can I solve this integral? Image link: http://oi61.tinypic.com/2jeoga1.jpg I tried to solve it: x^2/2 from 4 to 0. [(4^2/2)-(0^2/2)]=8 but its wrong. Do I have to multiply base*height/2 because ...
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### Trigonometric Substitution

I am having trouble with this problem even though everything I did seemed right to me since we went over a similar one in my class. I used the method of setting up a triangle, my hypotenuse is ...
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### Cross section with equilateral triangles and integration

Hello guys so I needed help with a problem which is: Let $S$ be the solid with ﬂat base, whose base is the region in the $xy$-plane deﬁned by the curves $y=e^x$, $y=−2$, $x=1$ and $x=3$, and ...
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### Finding the line integral around a triangle

How can I determine $\int xy \;ds$ of a triangle with points $(0,0)$, $(1,0)$ and $(1,1)$ *The integral has the letter $C$, which I am not sure how to input here. I know it may seem easy, but I am ...
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### Why Doesn't This Integral $\int \frac{\sqrt{x^2 - 9}}{x^2} \ dx$ Work?

I am trying to solve this integral, which is incorrect compared to Wolfram|Alpha. Why doesn't my method work? Find $\int \frac{\sqrt{x^2 - 9}}{x^2} \ dx$ Side work: ...
Evaluate the integral using trigonometric substitutions. $$\int{ x\over \sqrt{3-2x-x^2}} \,dx$$ I am familiar with using the right triangle diagram and theta, but I do not know which terms would ...