m1 is the mass of square wooden sheet of side a & m2 is the mass of removed square portion of side b. x-coordinate of C.O.M. of remaining L-shaped sheet. λ is areal mass density ⇒ m1=λa2,m2=λb2 Xcm=
λ(a2)(
a
2
)−λ(b2)(
b
2
)
λa2−λb2
Xcm=
1
2
(
a3−b3
a2−b2
) similarlyYcm=
1
2
[
a3−b3
a2−b2
] centre of mass lies on point P (b, b) ⇒ Xcm=b&Ycm=b