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## Comment on

Parallel or Not## Can you please explain how

## The important thing to

The important thing to recognize that the rule for parallel lines goes in BOTH directions. Here's what I mean.

IF the two lines are parallel, THEN we know that ∠e + ∠b = 180 degrees.

We can also say that, IF ∠e + ∠b = 180 degrees, THEN the two lines are parallel.

More here: https://www.gmatprepnow.com/module/gmat-geometry/video/858

## Can you explain this one , As

## If ∠e = 60 and ∠b = 120, then

If ∠e = 60 and ∠b = 120, then the two lines are definitely parallel.

Notice that, if ∠e = 60, then ∠d = 120 (since angles on a line add to 180 degrees)

This means ∠d = ∠b

If ∠d = ∠b, then we can be certain that lines 1 and 2 are parallel.

Conversely, we can also say that, if lines 1 and 2 are parallel, then it must be the case that ∠d = ∠b

For more on this, watch https://www.gmatprepnow.com/module/gmat-geometry/video/858 (starting at 5:40)

Does that help?

Cheers,

Brent

## Okay make sense , thanks for

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