Question 894451
The base is ON the line x=0; the base IS NOT x=0.


The vertex point is to the left of the y-axis, and the base is on the y axis.  The triangle as you described is a right triangle of the 45-45-90 type.  If you sketch this and have adequate intuition, you see two perpendicular lines containing (-2,-3).  Another fact you should quickly find is that distance from (-2,-3) to the base is |2|, or 2. 


You are looking for some algebra and coordinate geometry here in a more formal way, but my sketch on paper shows a segment on the y axis of length 4 units.  This isosceles triangle is cut into two smaller such triangles sharing the 2-unit length side between them, distance from (-2,-3) to the y-axis.


Slopes of the two longer (hypotenuse) segments are 1, and -1.  
y-intercepts are (0,-1) and (0,-5).


You can find the "equations" of the lines containing those sides any way you want.  Just you can continue knowing the three vertices of (-2,-3); (0,-1); and (0, -5).


{{{graph(300,300,-5,2,-5,2,x-1,-x-5)}}}