Yeah I know this is pretty basic, but I just can't think of it right now.(adsbygoogle = window.adsbygoogle || []).push({});

The slope of the wire is tan(theta) = y' = dy/dx

which yields sin(theta) = y' / sqrt (1 + y'^2)

How do you get from the first line to the second one?

this is what I I have done:

x^2 + y^2 = 1

cos^2(theta) + sin^2(theta) = 1

so cos^2(theta) = 1 - sin^2(theta)

so cos(theta) = sqrt (1 - y^2).

And

tan(theta) = sin(theta) / cos (theta).

So using tan(theta) = y' = dy/dx

sin(theta) / cos (theta) = y'.

sin(theta) = y' cos(theta)

plugging in what we got for cos earlier

sin(theta) = y' [sqrt (1 - y^2)]

now I am stuck.

I am just using this example to try and figure out how to do it. I actually want it in the form cos(theta) = something * x'.

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# Homework Help: Trig substitutions

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