The correct option is A 9xy=ab
Let the centroid be G,
Then
G=(x1+x2+x33,y1+y2+y33)
Here
(x1,y1)=(asect,btant)
(x2,y2)=(−atant,bsect)
(x3,y3)=(0,0)
Hence
G=(asect−atant3,btant+bsect3)
Or
G(x,y)=(asect−atant3,btant+bsect3)
Therefore
x=asect−atant3
Or
3x=asect−atant ..(i)
And
y=bsect+btant3
Or
3y=bsect+btant ...(ii)
Hence
3x×3y=(asect−atant)(bsect+btant)
9xy=ab(sect−tant)(sect+tant)
9xy=ab(sec2t−tan2t)
9xy=ab(1)
Or
9xy=ab