We report on the magnetization reversal behavior of sub 100-nm triangular shaped Ni80Fe20 dot array fabricated by nanosphere lithography. Hysteresis loops measured by magneto-optical Kerr effect magnetometry are classified into single and double-switched loops in 45 nm, 80 nm and 100 nm triangular nanomagnets. Micromagnetic simulations show that a plateau observed in the double-switched loop in the 100-nm triangular nanomagnet is due to the formation of a metastable mediating V state. (C) 2012 Elsevier B. V. All rights reserved.