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\(\large \begin{array}{lllcc} &&&x&y\\ &&rectangular&-1,& \sqrt{3}\\ &&&x&y\\ &&polar&r,& \theta\\ \quad \\ \quad \\ r^2 = x^2 + y^2 \implies r = \sqrt{x^2 + y^2}\\ \quad \\ \theta = tan^{-1}\left(tan\left(\cfrac{y}{x}\right)\right) \end{array}\)
so, what do you get for "r"?
sq rt 10?
and theta 6.14?
hmm... I should correct that \(\bf r^2 = x^2 + y^2 \implies r = \sqrt{x^2 + y^2}\\ \quad \\ tan(\theta) = \cfrac{y}{x} \implies \theta = tan^{-1}\left(\cfrac{y}{x}\right)\)
same for r, theta -1.04?
\(\bf r = \sqrt{(-1)^2+(\sqrt{3})^2} \implies r = \sqrt{(-1)^2+(\sqrt{3^2})} \implies r = \sqrt{1+3}\)
r=2..
yeap, so r = 2, and \(\bf \theta = tan^{-1}\left(\cfrac{y}{x}\right) \implies \theta = tan^{-1}\left(\cfrac{\sqrt{3}}{-1}\right) \implies \theta = tan^{-1}\left(-\sqrt{3}\right)\)
if you check your Unit Circle, that angle is there :)
negative sq rt 3 is on the unit circle?
well, anyhow, lemme make it ... this way one sec
\(\bf tan(\theta)= \cfrac{sin(\theta)}{cos(\theta)}\\ \quad \\ \quad \\ sin(\theta) = -\cfrac{\sqrt{3}}{2}\qquad\qquad cos(\theta) = \cfrac{1}{2}\\\quad \\ \quad \\ tan(\theta) = \cfrac{-\frac{\sqrt{3}}{2}}{\frac{1}{2}} \implies -\cfrac{\sqrt{3}}{\cancel{2}} \times \cfrac{\cancel{2}}{1} \implies -\sqrt{3}\)
do you see now the angle where \(\bf sin(\theta) = -\cfrac{\sqrt{3}}{2}\qquad\qquad cos(\theta) = \cfrac{1}{2}\)
300 degrees of 5pi/3?
or*
yeap, at 5pi/3 tangent is \(\bf -\sqrt{3}\)
so that makes the coordinates 2, 300?
keep in mind that, I could have gotten also angle at \(\bf \cfrac{2\pi}{3}\) and that one also has a tangent of \(\bf -\sqrt{3}\) however it would be OUTSIDE THE RANGE of the \(\bf tan^{-1}\) function since the arcTangent function range is between \(\bf -\cfrac{\pi}{2}\ and \ \cfrac{\pi}{2}\)
yes, the polar coordinates will be \(\bf (2, 300^o) \ or \ \left(2, \cfrac{5\pi}{3}\right)\)
cool thanks.
yw
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