JEE MAIN - Mathematics (2019 - 10th January Evening Slot - No. 19)

Two sides of a parallelogram are along the lines, x + y = 3 & x – y + 3 = 0. If its diagonals intersect at (2, 4), then one of its vertex is :
(2, 1)
(2, 6)
(3, 5)
(3, 6)

Explanation

JEE Main 2019 (Online) 10th January Evening Slot Mathematics - Straight Lines and Pair of Straight Lines Question 109 English Explanation
Solving

$$\matrix{ {x + y = 3} \cr {x - y = - 3} \cr } \,\, > \,\,A\left( {0,3} \right)$$

and  $${{{x_1} + 0} \over 2} = 2;\,\,{x_i} = 4$$

similarly y1 = 5

C $$ \Rightarrow $$  (4, 5)

Now equation of BC is x $$-$$ y = $$-$$ 1

and equation of CD is x + y = 9

Solving x + y = 9 and x $$-$$ y = $$-$$ 3

Point D is (3, 6)

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