1. PROVING A QUADRILATERAL IS AN ISOSCELES TRAPEZOID

2. USE SLOPE 4 TIMES AND DISTANCE 2 TIMES
You need to use the slope formula 4 times to show there’s 1 pair of parallel sides and 1 pair of sides not parallel (This proves it’s a trapezoid only).
You need to use the distance formula 2 times, either of the legs OR the diagonals, to show they are congruent in length.
Conclusion: It’s an isosceles trapezoid bc there’s 1 pair of parallel sides and 1 pair of sides not parallel and either the legs OR diagonals are congruent.