A Rāmāṉujaṉ identity (MathML test)

In a letter to Godfrey Harold Hardy, Srīṉivāsa Rāmāṉujaṉ Aiyaṅkār asserts that:

1 1 + e - 2 π 5 1 + e - 4 π 5 1 + e - 6 π 5 = 5 1 + 5 3 / 4 5 - 1 2 5 / 2 - 1 5 - 5 + 1 2 e 2 π / 5