Which step of proving theorem suggest to use working backward strategy?

What is the commonly used form of writing proofs when proving using indirect proof ?

Which of the following terms is accepted to be true without proof?

Deductive reasoning is needed to prove ________________.

What statement can be drawn out from the given ∠A =30º and ∠B = 60º ?

What would be the reason for the correct drawn out statement in # 5?

 Which part of this theorem is the hypothesis? In a triangle if one side is longer than another side, then the angle opposite the longer side is larger than the angle opposite the shorter side

Which part of the theorem  "In a triangle if one side is longer than another side, then the angle opposite the longer side is larger than the angle opposite the shorter side" 

In ∆PQR if m ∠R = 90º, which of the following statements is false?

In triangle ABC, ∠A is greater than ∠ B. To prove that BC is longer than AC by using indirect proof, which of the following must be the first statement?