KöMaL 2020 B5093

The intersection of two congruent regular pentagons is a decagon with sides of $a_1, a_2, \ldots, a_{10}$ in this order. Prove that $a_1a_3+a_3a_5+a_5a_7+a_7a_9+a_9a_1 = a_2a_4+a_4a_6+a_6a_8+a_8a_{10}+a_{10}a_2.$

Official text KöMaL. Quoted with source.

Solutions

No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.

Add a solution

Solutions

Similar problems