Surface temperatures of two stars in an eclipsing binary are $T_1$ and $T_2$ $(T_1>T_2)$, and the corresponding radii are $R_1$ and $R_2$ $(R_1>R_2)$, respectively. The total intensity of light is plotted as a function of time, this is called a light curve. The intensities of the incident light from the stars corresponding to the minima are $90$ and $63$ percent of the maximum intensity, $I_0$, received from both stars.

Use the diagram to find the ratio ${T_1}/{T_2}$.