Quadrilateral ABCD is a parallelogram. The coordinates are A (2,4), B (4,7), C (5,1). What is the coordinate of D?

I've tried graphing but I wish to do this algebraically. How should I start?

Question

Quadrilateral ABCD is a parallelogram. The coordinates are A (2,4), B (4,7), C (5,1). What is the coordinate of D?

I've tried graphing but I wish to do this algebraically. How should I start?

anonymous · Answer

hi .. 
Here under simple sketch for your problem .. I'm sure its so easy when you draw it .
|dw:1328262109252:dw|

while its parallelogram ( all time mistake by right this word i keep copy paste :P ) 
then  shift  displacement between A B , the same between C D
first we want to find displacement 
B-A = ( 2, 3 )
D = C + (B-A ) = ( 7 , 4 ) 
That is all !