Question

answer both the question. the question are 9th STD

Answer 1

Here is ur answer--> a+b+c =2s (given)
we can also write it as b+c= 2s-a
L.H.S.= b2+c2-a2+2ab
=(b+c)2-a2 (eq.1)
Now put the value of b+c in eq. 1
=(2s-a)2 - a2
=4s2 + a2 - 4sa -a2
=4s2 - 4sa
=4s(s-a)=R.H.S.
Hence proved......
HOPE IT HELPS........