How would you show that the functions

$\displaystyle

F(x)=\frac{2}{\pi}\arctan\Big(\frac{x}{a}\Big), x \geq 0

$

with $\displaystyle a>0$

and

$\displaystyle G(x)=1-\exp(-\lambda x),x\geq0$

with $\displaystyle \lambda>0$

meet (only)once at some $\displaystyle x>0$?