In the triangles below, $\displaystyle{m}\angle{B}={m}\angle{A}\usepackage{cmbright}\Huge\$ and $\displaystyle{m}\angle{T}={m}\angle{M}\usepackage{cmbright}\Huge\$ .

What is the length of $\displaystyle{\overline{{{H}{A}}}}\usepackage{cmbright}\Huge\$ ?