What are the missing reasons in the proof?

Given: parallelogram upper A upper B upper C upper D with diagonal modifying above upper B upper D with bar
Prove: triangle upper A upper B upper D congruent to triangle upper C upper D upper B

Arefrigeration system at your company uses temperature sensors fixed to read celsius (°c) values, but the system operators in your control room understand only the fahrenheit scale. you have been asked to make a fahrenheit (°f) label for the high temperature alarm, which is set to ring whenever the system temperature rises above –10°c. what fahrenheit value should you write on the label?