Question 1093836
Sec x-tanx=-1
sec = tan - 1
sec^2 = tan^2 - 2tan + 1
tan^2+1 = tan^2 - 2tan + 1
-2tan = 0
tan = 0
x = pi, 2pi
----------
Check for extraneous solutions:
Sec x-tanx=-1
sec(pi) - tan(pi) =? -1
-1 - 0 = -1  OK
=====================
sec(2pi) - tan(2pi) =? -1
1 - 0 = 1 NG
==========================
Only x = pi