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If a + b + c = 2s, then the value of (s - a)2 + (s - b)2 + (s - c)2 + s2 will be-
Answer & Solution
Correct Answer:
Option
C
$$\eqalign{
& {\left( {s - a} \right)^2} + {\left( {s - b} \right)^2} + {\left( {s - c} \right)^2} + {s^2} \cr
& = \left( {{s^2} + {a^2} - 2sa} \right) + \left( {{s^2} + {b^2} - 2sb} \right) + \cr
& \,\,\,\,\,\,\left( {{s^2} + {c^2} - 2sc} \right) + {s^2} \cr
& = 4{s^2} + ({a^2} + {b^2} + {c^2}) - 2s(a + b + c) \cr
& = {(2s)^2} + ({a^2} + {b^2} + {c^2}) - \cr
& \,\,\,\,\,\,(a + b + c)(a + b + c) \cr
& = {(a + b + c)^2} + \left( {{a^2} + {b^2} + {c^2}} \right) - \cr
& \,\,\,\,\,\,{(a + b + c)^2} \cr
& = {a^2} + {b^2} + {c^2} \cr} $$
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