Question 1:
Since S is "a" units away from the origin, the coordinates of S must be (0, a)
The base is "c" units long, so the coordinates of T should be (c, a)
Z is "b" units away from the origin, so the coordinates must be (b, 0)
Since the length is "c" units, the coordinates of W must be (b + c, 0).
Thus, the last choice is your answer.
Question 2:
Since SW is 2r, the distance from S and W from the origin is "r" units.
Since S and W lie on the x axis, that means that the coordinates of S and W must be (-r, 0) and (r, 0), respectively.
We don't have to get the coordinates for T and Z to know the correct answer.
There's only one answer choice that satisfies the coordinates for S and W, and that answer is the third choice.
Question 3:
The origin is the midpoint of the base.
The base is 2a units long.
The base lies on the x axis.
This means that S is (-a, 0) and Z is (a, 0).
We don't need to get the remaining two points since there is only one answer choice that satisfies these two coordinates.
Your answer is the third choice.
Have an awesome day! :)