Sinkhole a circular sinkhole has a circumference of 75.36 meters. a week later, it has a circumference of 150.42 meters.
a. estimate the diameter of the sinkhole each week.
b. how many times greater is the diameter of the sinkhole now compared to the previous week.
need this by tomorrow and i need work to show for the answer.

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

Precalculus question, image attached.

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.