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Question : 30 of 160
Marks:
+1,
-0
Solution:
Given,
A=+2+3,B=7−P=−2+3+5If
P divides
AB in the ratio
m:n, then its harmonic conjugate
Q divides
AB in the ratio
−m:n.
Now,
AB=B−A‌=(7−1)+(0−2)+(−1−3)‌=6−2−4Let
P divides
AB in the ratio
m:n, so
‌P=‌‌⇒‌‌−2+3+5‌‌‌=‌‌⇒‌‌(m+n)(−2+3+5)‌‌‌=n(+2+3)+m(7−)Comparing the coefficients of
, and
on both sides
⇒‌−2(m+n)‌=n(1)+m(7)⇒‌−2m−2n‌=n+7m⇒‌−9m‌=3n⇒‌‌‌=−3m∴‌‌‌=‌⇒‌‌=‌Now using section formula,
Q‌=‌‌=‌‌=‌=‌+‌+2So, sum of scalar components of
Q‌=‌+‌+2‌=‌+2=4+2=6
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