# Probability – How to find the joint cumulative distribution function in this region?

Find the cumulative cumulative distribution function of

$$f (x, y) = begin {cases} 1 & 0 the x the 1, 0 the y the 1, 2y the x \ 0 & text {otherwise} end {cases}$$

If I use the definition $$F (x, y) = int _ {- infty} ^ x int _ {- infty} ^ y1 dudv$$ for all $$(x, y) in mathbb {R} ^ 2$$.

How do I define regions?

It's easy to show that for the region $$x <0, y <0$$ then $$F (x, y) = 0$$but I have trouble defining other regions.