Idk what to put for the shapes like i dont understand

In the following diagram it is given that dec,ab || dc, ad || eb, and ad is congruent to bc. a)why isn't abc a parallelogram even though it has a pair of parallel sides and a pair of congruent sides b)explain why be must be congruent to bc. further explain what type of triangle this makes triangle abc and what it tells you about angle 1 and angle 2c) finally why must angle 3 be congruent to angle 1? further, explain why we know that angle 3 is congruent to angle 2

Anna is constructing a line segment that is congruent to another segment ab. for the construction, which tool should be used to mesure segment ab

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)