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Browse Classroom Capsules and Notes

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Displaying 981 - 990 of 1211

The author presents a geometric proof of Machin's formula, which expresses \(\frac {\pi}{4}\) as the difference of two inverse tangent functions.

The author proves visually the law of cosines.

The author gives two applications of a method for finding a function \(g\) such that \(f(g(x)) \geq f(x)\).

The author visually expresses the cube of a number as an arithmetic sum.

A visual determination of the area of a right triangle is given using an inscribed circle.

An odd prime \(p\) has \((p-1)/2\) quadratic residues mod \(p\), and for relatively prime \(p\) and \(q\) there are \((p-1)(q-1)/2\) non-representable Frobenius numbers. The author discusses a...

An old and forgotten method for determining whether a quartic polynomial over the rationals is reducible is revived.

The Butterfly Theorem is generalized to include Sidney Kung's Butterfly Theorem.

The unique root of \(cos(x)=x\), the Dottie number, is a simple non-trivial example of a universal attracting fixed point. The author gives pedagogical examples for several courses ranging from...

A visual solution for an alternating sum of odd squares is presented.