P.o.t.W. #13 Solution
If the three angles of the triangle form an arithmetic sequence, then the middle angle must be \(60^\circ . This can be explained as follows. Let the three angles be \({\theta _1},{\theta _2} and \({\theta _3} , in order from smallest to largest. Given that the angles are consecutive terms of an arithmetic sequence, then \({\theta _1} can be expressed as \({\theta _1} = {\theta _2} - d and \({\theta _3} can be...