The two equal sides of an isosceles triangle with fixed base b are decreasing at
the rate of 3 cm per second How fast is the area decreasing when the two equal
sides are equal to the base 3 Find the intervals in which the function f given by
4sin
2
cos
( )
2
cos
x
x
x
x
f x
x
−
−
=
+
is (i) increasing (ii) decreasing