Answer:
Step by step
Remember, a reference angle is a positive acute angle that represents an angle θ of any measurement.
a)
, then its reference angle is
b)
is in the second cuadrant, then its reference angle is
c)
, then it is in the first cuadrant and the reference angle is .
d)
and it is in the third cuadrant, then its reference angle is
((-4)^5)^8 / ((-4)^7)^3
= (-4)^40 / (-4)^21
= (-4)^20