A visual proof that $$\sin 2x = 2\sin x \cos x, \quad \cos 2x = \cos^2 x−\sin^2x$$ The argument only requires similarity of triangles.
Credits: Fermat's Library on Twitter (@fermatslibrary)
A visual proof that $$\sin 2x = 2\sin x \cos x, \quad \cos 2x = \cos^2 x−\sin^2x$$ The argument only requires similarity of triangles.
Credits: Fermat's Library on Twitter (@fermatslibrary)
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