Answer:
17) A(-1,1) B(-1,4) C(5,1)
18) (From origin moving rightwards)
A(0,0) B(a, 0) C(a,a) D(0,a)
Explanation:
17) You just count the steps, how many steps left, right, up, or down
18) The first point is at the origin, so 0,0
The second point that lies on the x axis is (a,0) as it is a distance from the origin, 0 because it's on the x-axis.
The third point is (a,a) because it is a distance to the right of the origin AND a distance upwards from the x axis.
The fourth point (0,a) because it is on the vertical line (0) and is a distance above the origin.