2 tan
sin ;
0 when
3
dy
y
x
x y
x
dx
π
+
=
=
=
14 2
12
(1
)
2
;
0 when
1
1
dy
x
xy
y
x
dx
x
+
+
=
=
=
+
15 3 cot
sin2 ;
2 when
2
dy
y
x
x y
x
dx
π
−
=
=
=
16 Find the equation of a curve passing through the origin given that the slope of the
tangent to the curve at any point (x, y) is equal to the sum of the coordinates of
the point