In geometry, the elongated pentagonal gyrobirotunda is one of the Johnson solids (). As the name suggests, it can be constructed by elongating a "pentagonal gyrobirotunda," or icosidodecahedron (one of the Archimedean solids), by inserting a decagonal prism between its congruent halves. Rotating one of the pentagonal rotundae () through 36 degrees before inserting the prism yields an elongated pentagonal orthobirotunda (). Formulae The following formulae for volume and surface area can be used if all faces are regular, with edge length a: References External links Johnson solids