■ GDC is allowed ■(a) Given the figure below and the indicated lengths and angles, express \({\rm{\theta }}\) as a function of \(x\) and \(\alpha \).(b) Let \(\alpha = 20^\circ \). Use a graph of \({\rm{\theta }}\) as a function of \(x\) to estimate the value of \(x\) that maximizes \({\rm{\theta }}\). Give your answer accurate to three significant figures.