You should plot the three known points on graph paper and it will become obvious where the fourth point of a parallelogram should be.
Knowing the 2 points D & C;
The line through two distinct points (x1, y1) and (x2, y2) is given by
You should plot the three known points on graph paper and it will become obvious where the fourth point of a parallelogram should be.
Knowing the 2 points D & C;
The line through two distinct points (x1, y1) and (x2, y2) is given by
DC is parallel to AB - it's a parallelogram as it's parallel it will have the same gradient as AB you can work out the gradient by the difference in the y cor-ordinates divided by the difference in the x co-ordinates can't you?
That gives you the m in y=mx+c
now you just neet the y intercept for the c
you know the point C is on DC so you know values for x and y and you have m from step 1 so you can find c
A simple diagram should give immediately D as (6,7). Reason: BC and AD are parallel and B->C is 4 across (increase in x) and 4 up (increase in y) gives D as
(2+4,3+4) (ie. 4 across and 4 up from A) =(6,7). The equation of DC should now be easy.