Stage: 5 Challenge Level: 
Two perpendicular lines are tangential to two identical circles that touch. What is the largest circle that can be placed in between the two lines and the two circles and how would you construct it?
Golden ratio. Straight edge & compass constructions. alphas. Mathematical reasoning & proof. Tangents. Manipulating algebraic expressions/formulae. Quadratic equations. Circles. Stage 5 - Reviewed 2012. epsilons.
Published September 1999.
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