Answer:
sec(154.158°) = -1.1111
Explanation:
given data 
cos(theta°) = −0.9
to find out
sec(theta°)
solution
as we know that given equation 
cos(theta°) = −0.9 
theta° = 

theta° = 154.158 .................1
so now we find 
sec(theta°)
and we know 
sec(theta°) = 
 .................2
 .................2
sec(theta°) = 
 ..............3
 ..............3 
sec(theta°) = 
 
 
sec(154.158°) = -1.1111