Question

BD is the median of triangle ABC. F is a point on AB such that CF intersects BD at E and BE=ED. If BF =5cm. Then BA=?​

Answer 1

Answer:

AB=3 and FB=3×5=15 units

Step-by-step explanation:

Let |ABC| denote area of ABC

let |ABC|=12a,

as AD=DC,⇒|BDC|=|BDA|=12a2=6a

as BE=ED,⇒|BEC|=|DEC|=6a2=3a,

let |BFE|=x,⇒|DFE|=x,

⇒|AFD|=|BDA|−|BDF|=6a−2x

As AD=DC,⇒|AFD|=|CFD|,

⇒6a−2x=3a+x

⇒x=a

⇒|CFB|=3a+x=4a

=> AB:FB=>|ABC|:|CFB|=12a:4a=3:1

=>AB=3 and FB=3×5=15 units