# Can someone please explain how to do #13?

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### 1 Answer

Usually, these kinds of problems are done by starting with the given. Following is the complete proof:

Statement 1:

`t _|_l`

Reason 1:

** Given**

Statement 2:

`m /_1=90`

Reason 2:

Definition of perpendicular lines

Perpendicular lines form right angles, angles with measure 90 degrees

Statement 3:

`l || n`

Reason 3:

Given

Statement 4:

`/_2 cong /_1 o r /_1 cong /_2`

Reason 4:

Corresponding Angles are Congruent

When a transversal cuts through two parallel lines, corresponding angles generated are congruent to each other.

Statement 5:

`m /_2 = 90`

Reason 5:

Substitution property. Using statements 2, and 4, we derive statement 5.

Statement 6:

`t _|_ n`

Reason 6:

Definition of perpendicular angles

QED.