)=35 ‌⇒‌‌2s2−(a+b+c)s+ab=35 ‌‌‌[∵s(s−a)(s−b)(s−c)=∆2] ‌⇒‌‌2s2−2s2+ab=35[∵a+b+c=25] ‌⇒‌‌ab=35‌‌...‌ (i) ‌ ‌∵‌‌r2r3+π1=63 So, ‌‌bc=63‌‌... (ii) ∵‌‌r3r1+r⋅r2=45 So, ca=45‌‌... (iii) From Eq. (i), (ii) and (iii), we get a=5,b−7,c=9 Hence, 2s=a+b+c=5+7+9=21