"In an  equilateral triangle `A B C`the side `B C`is  trisected at `D`. Prove  that `9\ A D^2=7\ A B
Channel: Doubtnut
Date: 2020-07-05

"In an
  equilateral triangle `A B C`
the side `B C`
is
  trisected at `D`
. Prove
  that `9\ A D^2=7\ A B^2`"