#e^(i theta) = cos theta + i sin theta#
#e^(((3pi)/2) i )= cos ((3pi)/2) + i sin ((3pi)/2)#
#~~> - i#, III Quadrant
#e^(((13pi)/8)i) = cos ((13pi)/8) + i sin ((13pi)/8)#
#=> 0.3827 - 0.9239 i#, IV Quadrant.
#e^(((3pi)/2)i) - e^(((13pi)/8)i) = -0.3827 - i + 0.9239 i #
#color(chocolate)(=> -0.3827 - 0.0761 i #, IV Quadrant.