C4- Vectors

will upload in a min

need help in last part

what I am done so far is
they mention that the area is twice .I 3sqroot3 which becomes 6sqroot3
then then I use formula
1/2 (AD)*(SQROOT 24) * Sin30=6sqroot 3
to find AD length

then I try to use modulus here
I set an expression
as D lies on L

(..........)^2=AD (ad=6sqroot 2)
and then take a square to remove sqroot
and get an equ
6lenda^2 -24 lenda-19 =0


(I thought that by doing that I will get two values of lenda and will sub that in
-1+2lenda
lenda-4
6-lenda

Could you please upload an image of your working?

the height of triangle CDA will be the same as that of triangle CAB.

it follows that the base of triangle CDA must be double that of triangle CAB.... in other words length AD = 2AB

suppose AB were 8 units long. then D could be 16 units away from A so that DAB was a line, or 16 units away from A so that ABD was a line.

thank you
Finally got right answer

so the whole point is if the area gets double it means it base gets double