The area of the rectangle is changing at
0.75 sq.cm/min
Let
x
and
y
be the base and height of the rectangle.
x
=
0.5
cm is constant :. dx/dt=0#. Area of the rectangle
is
A
=
x
⋅
y
. Differentiating both sides we get
d
A
d
t
=
d
x
d
t
⋅
y
+
d
y
d
t
⋅
x
;
y
=
1.5
,
d
y
d
t
=
1.5
cm /min.
∴
d
A
d
t
=
0
⋅
1.5
+
1.5
⋅
0.5
=
0.75
sq.cm/min.
The area of the rectangle is changing at
0.75
sq.cm/min
