A picture
is hung from a supporting wire and the base of the picture is supported by a shelf.
In this
example the position of the supporting wire is known including the angle that it makes with the
vertical. The picture is taken to be uniform so its weight acts through the middle of the picture.
By
drawing first the weight (mg - both size and direction are known), and then the tension in the wire (T - size
and direction known once again) the size and direction of the reaction at the shelf (R) can be
found.