In: Math
f(x) = 10/cos-1(x). Use calculus to determine:
a) all critical values
b) any local extrema
c) any absolute extrema
d) the intervals where f is increasing/decreasing
e) any points of inflection rounded to the thousandths place
f) intervals where f is concave up/down
No interval was specified so I assumed 0<x<2pi
also I didn't get any concavity not sure if I'm right or not.
I got x= pi as the critical value as well as the relative and absolute minimum extrema.
would greatly appreciate some help
as arccos(x) or inverse of cos(x) is defined in domain [-1,1]
with range [0, pi]
as we can not have 0 in denomiantor, therefore x can not be
equal to 1, this is the reason
.
as arccos(x) and square root of 1-x^2 , both are always positive. therefore f'(x) > 0,
hence no critical root, and f(x) is increasing function in tis domain.
with lowest value when x = -1, that is f(x) = 10/pi = 3.1831.
On solving from calculator :
f''(x) = 0 at x ~=-0.6580
The point of inflection is x = -0.6580.
Graph: