Answer
$\lambda_{max} = 5.0\times 10^{-7}~m$
Work Step by Step
We can find the wavelength at which the spectral radiancy is maximum:
$\lambda_{max}~T = 2.898\times 10^{-3}~m~K$
$\lambda_{max} = \frac{2.898\times 10^{-3}~m~K}{T}$
$\lambda_{max} = \frac{2.898\times 10^{-3}~m~K}{5800~K}$
$\lambda_{max} = 5.0\times 10^{-7}~m$
