Stage:5 Challenge Level:
If for a triangle $ABC$
$\tan(A - B) + \tan(B - C) + \tan(C - A) = 0$
what can you say about the triangle?
Mathematical reasoning & proof. Interactivities. Working systematically. Creating expressions/formulae. Visualising. Tangent. Periodicity. Trigonometric identities. Manipulating algebraic expressions/formulae. Generalising.
Published April 2000.
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