$\begin{array}{1 1}(a)\;2at\sqrt{1+t^2},2a\sqrt{1+t^2},2at^2,2a\\(b)\;2at\sqrt{1-t^2},2a\sqrt{1-t^2},2at^,4a\\(c)\;4at\sqrt{1+t^2},4a\sqrt{1+t^2},2at,8a\\(d)\;2at^2\sqrt{1-t^2},2a\sqrt{1-t^2},2at,6a\end{array}$
