In Figure -6 , in an equilateral triangle ABC, AD is perpendicular to BC , BE is perpendicula
Channel: Doubtnut
Date: 2020-04-19

In Figure -6 , in an equilateral triangle ABC, AD is perpendicular to BC , BE is perpendicular to AC and CF is perpendicular to AB . Prove that 4 (AD^2 +BE^2 +CF^2)=9AB^2description.