Question

The proof by indirect method is shown below. In which step does the contradiction appear?

Given: –→BD is not ⊥ ↔AC
Prove: m∠1 ≠ m∠2

Step 1: Assume m∠1 = m∠2
Step 2: ∠1 and ∠2 are linear pairs and supplementary angles
Step 3: ∠1 and ∠2 are right angles
Step 4: –→BD ⊥ ↔AC
Step 5: m∠1 ≠ m∠2
Step 1 Step 5
Step 2 Step 4

Answer 1

Look at step 1 vs step 5

Answer 2

Step 4.

Answer 3

Yes. I suppose it does appear at 4 before 5.

Answer 4

hmmm

Answer 5

We were given that they are not perpendicular and yet our assumption implies otherwise

Answer 6

u think 4 is the best answer

Answer 7

I would say so. However, the contradiction is more obvious in 5 than 4.