Question 1005478
Same algebra concepts and skills from your earlier algebra courses.  Solve for cosine of theta in terms of sine of theta.  What would you do if you had x^2+y^2=k, and you wanted to solve for x in terms of y?  And then how do you finish this properly, to account for the square root?


{{{x^2+y^2=k}}}
{{{x^2+y^2-y^2=k-y^2}}}
{{{x^2+0=k-y^2}}}
{{{x^2=k-y^2}}}
{{{x=0+-sqrt(k-y^2)}}}




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The addition of 0 was included to make the rendering on the site work.