Thousand Words
Stage: 5 Challenge Level:

Draw a simple diagram which makes it clear that the following
inequality holds for any complex numbers $z$ and $w$ $$|z-w|\geq
|z| -|w|$$
Now draw another simple diagram which makes it clear that the
following inequality holds for any real numbers $\alpha>
\beta$
$$|e^{i\alpha}-e^{i\beta}|\leq \alpha - \beta$$
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