3.Write the coordinates of the vertices of each of these adjoining figures.

We have the required coordinates as follows:
For rectangle OABC are:

O(0, 0), A(2, 0), B(2, 3), C(0, 3)

For parallelogram PQRS:

P(4, 3), Q(6, 1), R(6, 5), S(4, 7)

For triangle KLM :

K(10, 5), L(7, 7), M (10, 8).