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  1. If a + b + c = 2s, then
    (s − a)2 + (s − b)2 + (s − c)2 + s2
    is equal to
    a2 + b2 + c2
    1. a2 + b2 + c2
    2. 0
    3. 1
    4. 2
Correct Option: C

Expression =
(s − a)2 + (s − b)2 + (s − c)2 + s2
a2 + b2 + c2

=
s2 − 2sa + a2 + s2 + b2 − 2sb + s2 − 2sc + c2 + s2
a2 + b2 + c2

=
4s2 + a2 + b2 + c2 − 2s(a + b + c)
a2 + b2 + c2

=
4s2 + a2 + b2 + c2 − 4s2
= 1
a2 + b2 + c2



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