Guest: 2X, given sinX= 2/5 and cos X <0
sinx is pos therefore it is 1st or 2nd quad
cosx is neg therefor 2nd or 3rd quad
Therefore x must be in the second quadrant
sin
-1(2/5) = 23.578.. (first quad)
X = 180-23.578... = 156.4218...
In general X=156.4218 + 360N Where N is in the set of integers
2x = 312.84...
2x = 312 degrees 50minutes and 37 seconds +720N Where N is in the set of integers (to the nearest second)
+118725 
