Help? Me please

Which math sentence can be used to determine if the triangle is a right triangle?

Write the expression 7x^3-28xy^2 as the product of 3 factors

Me! i'm really confused the isosceles trapezoids, abcd and efgh, are similar quadrilaterals. the scale factor between the trapezoids is 2: 3, line gh = 6 centimeters, line ad = 8 centimeters, and line ab is three times the length of line dc . use complete sentences to answer the following prompts and include all of your calculations in your final answer. a. write a similarity statement for each of the four pair of corresponding sides. b. write a congruence statement for each of the four pair of corresponding angles. c. determine the perimeter for each of the isosceles trapezoids.