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    by using the substitution 3u=2tanx find the area enclosed by the ellipse and the lines x=0 and x=pi/4 where x is theta btw...
    r^2=36sec^2x/9+4tan^2x

    help!!
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    Use the fact that sec^2(x)= tan^2(x) + 1, and simply substitue everything in and simplify accordingly.
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    (Original post by Radioactivedecay)
    Use the fact that sec^2(x)= tan^2(x) + 1, and simply substitue everything in and simplify accordingly.
    yes, i understand this, but i want to sub in the dx with the u's but its confusing me...
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    3u=2tanx

    3du/dx=2sec^2(x)

    rearrange for dx and substitute back in.
 
 
 
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Updated: March 13, 2018

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