Coordinate Geometry Question 140

Question: If $ A(3,5),B(-5,-4),C(7,10) $ are the vertices of a parallelogram, taken in the order, then the co-ordinates of the fourth vertex are

[Kerala (Engg.) 2005]

Options:

A) (10, 19)

B) (15, 10)

C) (19, 10)

D) (19, 15)

E) (e) (15, 19)

Show Answer

Answer:

Correct Answer: E

Solution:

(e) Mid point of $ A(3,5) $ and $ C(7,10) $ = $ M( 5,\frac{15}{2} ) $ Mid point of $ BD=M( 5,\frac{15}{2} ) $

$ B(-5,-4) $ and $ D(x,y) $ $ \frac{-5+x}{2}=5 $ ; $ x=10+5=15 $

$ \frac{-4+y}{2}=\frac{15}{2} $ ; $ y=15+4=19 $ Co-ordinates of fourth vertex $ D=(15,\ 19) $ .