$12.$ Two point sources separated by $12\mathrm{.}0$ cm are generating ripples in a ripple tank. The sources are in opposite phase. Point P is on the second nodal line and is located $19\mathrm{.}5$ cm from one source. If the distance between crests is $2\mathrm{.}5$ cm $,$ how far is P from the other source? State any assumptions you might make $($or show on a sketch$).(4$ marks$).$ This is a question on a grade $12$ Physics waves test