ABCD is bar mechanism, in which AD is the fixed link, and link BC, is in the form of a circular disc with centre P. In which one of the following cases P will be the instantaneous centre of the disc?
1
If it lies on the perpendicular bisector of link BC
2
If it lies on the intersection of the perpendicular bisectors of BC & AD
3
If it lies on the intersection of the perpendicular bisectors of AB & CD
4
If it lies on the intersection of the extension of AB and CD