In computing the radians of the 7/8 of the circle we must get the value of the angle subtended by the sector given that in one revolution of a circle is 360 degrees. Thus,
7/8*360= 315deg
convert degree to radians, multiply by pi/180
315deg x pi/180= 1.75 pi radiansThe angle subtended by 7/8 of circle is 1.75 pi radians