Area of a 3-D triangle in terms of its projections on 3 Cartesian planes?

Suppose a triangle $ABC$ with points $A(x_1, y_1, z_1)$ , $B(x_2,y_2,z_2)$ and $C(x_3,y_3,z_3)$ . Projection of this $\triangle ABC$ on $xy$ -plane is of area $A_1$ . Projection on $yx$ -plane is of area $A_2$ and projection at $zx$ -plane is of area $A_3$ . What is the area of $\triangle ABC$ in terms of $A_1$ , $A_2$ , and $A_3$ ?