Answer
A(0,0)
B(a,0)
C(a,5)
Work Step by Step
First, we find the coordinates of A.
From the picture, we see vertex A is located at the origin. Hence the coordinates of A are $(0,0)$.
Next, we find the coordinates of B.
We are given the $x$-coordinate of B, which is $a$, and from the picture, we see B lies on the $x$-axis, which means the $y$-coordinate of B is $0$. Thus vertex B has coordinates $(a,0).$
Now vertex C is located 5 units above vertex B. So C has the same $x$-coordinate as B, which is $a$, and it's $y$-coordinate is 5 more than that of B's $y$-coordinate. Hence the coordinates of C are $(a,5)$.
