<PRE><B>Question 566841</B>
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Because the tangent of the angle formed by a radius to the unit circle and the positive horizontal axis is equal to the slope of the line containing the radius segment (sine is the rise, cosine is the run, and tangent is sine divided by cosine)


*[tex \LARGE \ \ \ \ \ \ \ \ \ \  L_1\ \perp\ L_2 \ \ \Leftrightarrow\ \ m_1\ =\ -\frac{1}{m_2}\ \text{ and } m_1,\, m_2\, \neq\, 0]


John
*[tex \LARGE e^{i\pi} + 1 = 0]
My calculator said it, I believe it, that settles it
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