Rectangular → polar, third quadrant

A point in the third quadrant: $\displaystyle x=-3$, $\displaystyle y=-2.5$. A negative number starts with the (-) key, not with the - key. Press and for Pol, then the and 3. Press and for the comma, then the and 2.5. Press and . $\displaystyle r$ is r=3.905124838, and $\displaystyle \theta$ is θ=−140.1944289 degrees. The angle is negative because it is measured clockwise: $\displaystyle \theta$ is always given between $\displaystyle -180^{\circ}$ and $\displaystyle 180^{\circ}$.

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