Answer:
f(x) = 3 cos2(x) − 6 sin(x), 0 ≤ x ≤ 2π
We plot the function using a graphing calculator (See attached image below)
a) 1. Find the interval on which f is increasing.
f(x) increases for
x ∈ [π/2 , 7π/6] ∪ [3π/2, 11π/6]
2. Find the interval on which f is decreasing
f(x) decreases for
x ∈ [0 , π/2) ∪ (7π/6, 3π/2) ∪ (11π/6, 2π]
(b) Find the local minimum and maximum values of f
Local minimum. f = -9
Local maximum. f = 4.5
(c) 1. Find the inflection points
Please see second image attached
Points,
(x,y) = (2.50673, -2.66882)
(x,y) = (4.14456, 3.79382)
(x,y) = (5.28022, 3.79382)
2. Find the interval on which f is concave up.
x ∈ [0 , 2.50673] ∪ [4.14456, 5.28022]
3. Find the interval on which f is concave down.
x ∈ (2.50673, 4.14456) ∪ (5.28022, 2π]
Let's assume time taken by plane on one way distance as 't'
The total flying time in both directions was 10.5 hr
so, time taken in other direction =10.5-t
now, we are given
A plane averaged 500 mph on a trip going east
so, total distance of one way is
total distance of other way is
now, we can that distance is same from both sides
so, we get
now, we can solve for t
now, we can find one way distance
miles..............Answer