A sinusoidal sketching for peak 60V applied to a diode as shown
First, by KVL, we have:

\$V_O = 15V + V_D\$

Second, there are two regions of operation per cycle of the AC voltage source.  Assuming an ideal diode, they are:

(1) \$V_D = 0V\$ when \$I_D &gt; 0\$ (the diode is a short circuit for forward current)

(2) \$I_D = 0A\$ when \$V_D &lt; 0\$ (the diode is an open circuit for reverse current)

Can you take it from here?