In right angled triangle ABC,angle B=90degree and AB=√34unit.The coordinates of points B,C are(4,2)&(-1,y).if ar(ABC)=17units then find the value of y

you know that the area is

(AB*BC)/2 = (√34*BC)/2=17
BC = 34/√34 = √34

So, now you know that

5^2 + (2-y)^2 = 34
y = 5 or -1