The ratio of the area of the sector (S) to the area of the entire circle (C) is equal to the ratio of the angle subtended to form the sector (As) to the angle for the whole revolution (Ac)
S / C = As / Ac
Substituting the given,
S / 36 m² = 40 degrees / 360 degrees
Solving for S gives, S = 4. Thus, the area of the sector is 4 m².