Hi Zambo,
The 'y' in Q.1d.
is the difference in height between two triangles.
The height of the 38 degree triangle
subtracted from
the height of the 44 degree triangle.
Height being TAN x BASE,
so for 38 degrees we have (TAN 38 ) x 18 = height
thats (0.781 x 18 ) = 14.058
and for 44 degrees we have (TAN 44) x 18 = height
thats (0.965 x 18 ) = 17.370
Subract 14.058 from 17.370 leaving 3.312
I hope the method is clear,
my figures are slightly different,
i only went to third place decimal.
Best of luck,
John