Quadrilaterals

A | B |
---|---|

in these quadrilaterals, the diagonals are congruent | rectangle, square, isosceles trapezoid |

in these quadrilaterals, each of the diagonals bisects a pair of opposite angles | rhombus, square |

in these quadrilaterals, the diagonals are perpendicular | rhombus, square |

a rhombus is always a | parallelogram |

Accordingly, do consecutive interior angles equal 180?

The

**consecutive interior angles**theorem states that when the two lines are parallel, then the**consecutive interior angles**are supplementary to each other. Supplementary means that the two**angles add up to 180**degrees.Are consecutive angles of a parallelogram supplementary?

DEFINITION: A

**parallelogram**is a quadrilateral with both pairs of**opposite**sides parallel. THEOREM: If a quadrilateral has 2 sets of**opposite angles**congruent, then it is a**parallelogram**. * THEOREM: If a quadrilateral has**consecutive angles**which are**supplementary**, then it is a**parallelogram**.