k →Tangens: (Nogmaals verbeterd. Het begint laat te worden.) |
k →Bewijs: (Nogmaals.) |
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Regel 139:
& = \frac{\cos^2(x) + \sin^2(x)}{cos^2(x)} \\
& = \frac{1}{cos^2(x)} \\
& = \bigg(\frac{1}{\cos
& = \sec^2(x) & \Box
\end{align}</math>
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