Formula: A2_{2}2 = A1_{1}1(1 + βθ\beta \thetaβθ)
where β\betaβ = The area expansivity
θ\thetaθ = Change in temperature.
β\betaβ = 2α\alphaα
where α\alphaα = linear expansivity of the body.
⇒ β\betaβ = 2 x 0.000017
= 0.000034 K−1^{-1}−1
∴\therefore∴ A2_{2}2 = 100 (1 + (0.000034 x 70))
= 100(1 + 0.00238)
= 100(1.00238)
= 100.238 cm2^{2}2
= 100.24 cm2^{2}2 (to 2 d.p)
