If in the triangle ABC, B=450,then a4+b4+c4 is equal to
2a2 (b2 +c2)
2c2 (a2 + b2)
2b2 (a2 + c2)
2 (a2b2 + b2c2 + 3a2c2)
cosB=c2+a2−b22ac⇒1√2=c2+a2−b22ac⇒√2ac=c2+a2−b2On squaring both sides, we get2a2c2=c4+a4+b4+2c2a2−2(c2+a2)b2⇒c4+a4+b4=2(c2+a2)b2