what is the square root of 81 by the difference between the product of -1 and -3 and the square root of 4

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

If sr is 4.5cm and tr is 3cm, what is the measure in degrees of angle s?

What makes a trapezoid an isosceles trapezoid?