Asquare sheet of paper has area 15textcm2. the front side is white and the back side is black. a corner of the sheet is lifted and placed so that the crease is at a 45circ angle. if the fold is such that the visible black area is equal to the visible white area, how many centimeters long is the crease? express your answer in simplest radical form. [asy] unitsize(2 cm); pair translate = (1.5,0); draw((0); draw(shift(translate)*((1, 1 - sqrt(2/,,, - sqrt(2/3), ; draw((1, 1 - sqrt(2/ - sqrt(2/3),1),dashed); filldraw(shift(translate)*((1 - sqrt(2/3), 1 - sqrt(2/, 1 - sqrt(2/ - sqrt(2/3), ),black); [/asy]