Coordinate Geometry Question 169
Question: If the points $ (a,b),(a’,b’) $ and $ (a-a’,b-b’) $ are collinear, then
[RPET 1999]
Options:
A) $ ab’=a’b $
B) $ ab=a’b’ $
C) $ aa’=bb’ $
D) $ a^{2}+b^{2}=1 $
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Answer:
Correct Answer: A
Solution:
$ \frac{a-{a}’-{a}’}{{a}’-a}=\frac{b-{b}’-{b}’}{{b}’-b} $
$ \Rightarrow \frac{a-2{a}’}{{a}’-a}=\frac{b-2{b}’}{{b}’-b} $
$ \Rightarrow \frac{a}{{{a}’}}=\frac{b}{{{b}’}}\Rightarrow a{b}’={a}‘b. $
BETA
