Question

In parallelogram ABCD, A (0,0),B(a,b)and D(c,0)are three of it's vertices, what are the coordinates of C in terms of a,b,c

Answer 1

I would use slopes
Let point C be (x,y)
In my diagram , AD || BC , and both are horizontal.
then x-a = c-0
x = c+a

slope AB = slope CD
b/a = y/(x-c)
y = b(x-c)/a
= b(c+a + a)/a
= b(c + 2a)/a