Solve and check the equation. 3x=18

Write two subtraction equations that are equivalent to 5 + 12 = 17.

Sketch one cycle if the cosine function y=2cos2theta

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.