Thread: Help with postulates and theorems

1. Help with postulates and theorems

State the postulate or theorem that justifies each statement
Given: c ll d

1.) ∠5 ≅ ∠7
2.) ∠3 ≅ ∠6
3.) m∠6 + m∠7 = 180
4.) bd

I'm really lost, can someone please explain to me how this is done?

2. Originally Posted by zoe
State the postulate or theorem that justifies each statement
Given: c ll d

1.) ∠5 ≅ ∠7 corresponding angles are equal
2.) ∠3 ≅ ∠6 alternate-interior angles are equal
3.) m∠6 + m∠7 = 180 consecutive interior angles are supplementary
4.) bd two lines in a plane perpendicular to the same line

I'm really lost, can someone please explain to me how this is done?
Geometry: Testing for Parallel Lines - CliffsNotes

3. Originally Posted by zoe
State the postulate or theorem that justifies each statement
Given: c ll d

1.) ∠5 ≅ ∠7
2.) ∠3 ≅ ∠6
3.) m∠6 + m∠7 = 180
4.) bd

I'm really lost, can someone please explain to me how this is done?
You should start by making a list of postulates and theorems about parallel lines and seeing which correspond to the situation in each line.

4. Originally Posted by zoe
State the postulate or theorem that justifies each statement
Given: c ll d

1.) ∠5 ≅ ∠7

Postulate: If two parallel lines are cut by a transversal, then each pair of corresponding angles are congruent.

2.) ∠3 ≅ ∠6

THEOREM: If two parallel lines are cut by a transversal, then each pair of alternate interior angles are congruent.

3.) m∠6 + m∠7 = 180

THEOREM: If two parallel lines are cut by a transversal, then each pair of consecutive interior angles are supplementary.

4.) bd

THEOREM: In a plane, if a line is perpendicular to one of two parallel lines, then it is perpendicular to the other.

I'm really lost, can someone please explain to me how this is done?
Memorize these!

5. Thanks, but how exactly did you come up with those answers? I don't understand how I'm supposed to solve these kinds of questions. I really don't understand postulates and theorems at all. Could someone break it down for me?