Let A be an irreducible (entrywise) nonnegative nˆn matrix with eigenvalues ρ, λ 2 " b`ic, λ 3 " b´ic, λ 4 ,¨¨¨, λ n , where ρ is the Perron eigenvalue. It is shown that for any t P r0, 8q there is a nonnegative matrix with eigenvalues ρ`t, λ 2`t , λ 3`t , λ 4¨¨¨, λ n , whenevert ě γ n t with γ 3 " 1, γ 4 " 2, γ 5 " ? 5 and γ n " 2.25 for n ě 6. The result improves that of Guo et al. Our proof depends on an auxiliary result in geometry asserting that the area of an n-sided convex polygon is bounded by γ n times the maximum area of a triangle lying inside the polygon.