ABC is a right triangle, right angled at A and D is mid point of AB. Prove that, BC²=CD²+3BD²
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here is the answer....
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In triangle ABC
By pythagoras theorem
BC2=AB2+AC2....(1)
In triangle ADC
CD2=AC2+AD2
AC2=CD2-AD2
from (1)
BC2=AB2+CD2-AD2
BC2=(AD+BD)2+CD2-AD2
BC2=AD2+2AD.BD+BD2+CD2-AD2
BC2=2AD.BD+BD2+CD2
since D is a midpoint of AB
AD=BD
BC2=2BD2+BD2+CD2
BC2=3BD2+CD2
By pythagoras theorem
BC2=AB2+AC2....(1)
In triangle ADC
CD2=AC2+AD2
AC2=CD2-AD2
from (1)
BC2=AB2+CD2-AD2
BC2=(AD+BD)2+CD2-AD2
BC2=AD2+2AD.BD+BD2+CD2-AD2
BC2=2AD.BD+BD2+CD2
since D is a midpoint of AB
AD=BD
BC2=2BD2+BD2+CD2
BC2=3BD2+CD2
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