Return x; y; coordinates of vertex C of triangle I would like to return the XY coordinates of vertex C using math formula. 
I have 5 input data what I always know and can be used for solution (green in the image): I know X; Y; coordinates of point A and point B (Ax, Ay, Bx, By), and I know the length of all three sides of triangle (AB, AC, AD). Please help how to get the values of X Y coordinate of point C, what is 70/30 in the example, but I have no formula to get back them.



I know that more than one solution of this formula, but:


Coordinates cannot be in negative areas. All coordinates must be positive.
I always use 1 direction for vertex labelling, but because I always know the length of AC and BC, I think to change the label from A to B will not change the position of C.


Thanks!
You can get the coordinates of C by using circle equations for one circle C_A with point A as center and AC as its radius and one circle C_B with point B as its center and BC as its radius.

Now you can calculate their intersection points, which leaves you with 2 points (iff C is not on a line between A and B).

I am not entirely sure how you want to determine which of the two candidates C_1 and C_2 is the correct one. If I understand correctly, you always label the triangle counterclockwise. There is a neat way to check this, so you should have everything to find your point.