Lessons for G.CO.C.9
Alternate and same side anglesAngles on opposite sides of the transversal and between the two lines.Lesson
Angle types and pairsAcute, right, obtuse; complementary, supplementary, vertical.Lesson
Corresponding anglesAngles in matching positions at the two crossings, congruent when the lines are parallel.Lesson
Adjacent angles and linear pairsTwo adjacent angles whose outer sides form a straight line, so their measures add to 180 degrees.Lesson
Proving alternate interior angles congruentCombining the corresponding angles postulate with a pair of vertical angles.Lesson
Proving angle pair theoremsUsing two linear pairs that share an angle to show the opposite angles must match.Lesson
Proving lines parallelUse the transversal angle pairs in reverse.Lesson
The parallel postulateThrough a point not on a line there is exactly one parallel line, the assumption Euclidean geometry rests on.Lesson
Vertical anglesThe opposite pair of angles formed when two lines cross, always equal in measure.Lesson
Printable Worksheets
Alternate and same side angles worksheet (PDF)Printable worksheet with answer keyPreview
Corresponding angles worksheet (PDF)Printable worksheet with answer keyPreview
Adjacent angles and linear pairs worksheet (PDF)Printable worksheet with answer keyPreview
Proving alternate interior angles congruent worksheet (PDF)Printable worksheet with answer keyPreview
Proving angle pair theorems worksheet (PDF)Printable worksheet with answer keyPreview
Proving lines parallel worksheet (PDF)Printable worksheet with answer keyPreview
The parallel postulate worksheet (PDF)Printable worksheet with answer keyPreview
Vertical angles worksheet (PDF)Printable worksheet with answer keyPreview