proof by contradiction

Which TWO statements below contradict each other.

• a ∥ b

• b ⊥ a

• a ∥ c

Tags

CCSS.HSG.CO.A.1

CCSS.4.G.A.1

Which TWO statements below contradict each other.

• Quadrilateral is a square.

• Quadrilateral has four equal sides.

• Quadrilateral has no right angles.

Tags

CCSS.HSG.CO.C.11

The first step of an proof by contradiction is to ____?

• write the given

• assume the negation of the given

• assume the negation of what you are trying to prove

• contradict the given

The second step of an proof by contradiction is to ____?

• assume the negation of the given

• assume the negation of what you are trying to prove

• conclude the prove is true

• contradict the given using logical statements based on the initial assumption

What assumption would you make to start the proof by contradiction of:

there can be only one 90 angle in a triangle

• here can be more than one 90 angle in a triangle

• <a+<b+<c=180

• <a+<b+<c≠180

• all the angles in a triangle add up to 180.