A thin prism with angle \( 5^\circ \) of refractive index \( 1.72 \) is combined with another prism of refractive index \( 1.9 \) to produce dispersion without deviation. The angle of second prism is ______.
\( 5^\circ \)
\( 6^\circ \)
\( 4^\circ \)
\( 4.5^\circ \)