Dear Deva
diagonals of rectangle bisect each other.let ABCD is rectangle. and A=(1,3), C=(5,1)
Mid point of diagonal AC is (3,2)
mid point of diagonal BD will also be (3,2) and given line is equation of BD
(3,2) will satisfy the equation
put y=2 and x=3
2=6+c
c=-4
All the best.
AKASH GOYAL
AskiitiansExpert-IITD
 
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LET ABCD is the rectangle  let A,C are (1,3) , (5,1) then         mid point of line AC is (3,2)         now mid point of line BD is same so line passing through B,D will pass mid point & (3,2) will satisfy the equation of line..  Y = 2X+C at (3,2) 2 = 3*2 + C C= -4
						

							Diagonals bisectors each other so mid point of given diagonal would also be mid point of other i.e, lies on equation and would satisfy so we get close =, - 4 on putting the point on line