3.4 x 109 by 2.1 x 106

For which rational expression is -2 an excluded value of x?

In the figure below, ∠dec ≅ ∠dce, ∠b ≅ ∠f, and segment df is congruent to segment bd. point c is the point of intersection between segment ag and segment bd, while point e is the point of intersection between segment ag and segment df. the figure shows a polygon comprised of three triangles, abc, dec, and gfe. prove δabc ≅ δgfe.

Alogical argument that is presented in graphical form using boxes and arrows is called?