Answer :
cos (X) + sin (X) = 0
Subtract cos(x) from each side:
sin(x) = -cos(x)
Divide each side by cos(x) :
sin(x) / cos(x) = -1
But sin/cos = tangent
tan(x) = -1
x = 135° and 315°
x = 3/4 pi radians and 7/4 pi radians
Subtract cos(x) from each side:
sin(x) = -cos(x)
Divide each side by cos(x) :
sin(x) / cos(x) = -1
But sin/cos = tangent
tan(x) = -1
x = 135° and 315°
x = 3/4 pi radians and 7/4 pi radians
