Counterexamples

Which of the following provide a counterexample to the claim:

"If two angles are supplementary, then they are not congruent."

•  $40\degree\ and\ \ 140\degree$ 

•  $80\degree\ and\ \ 80\degree$ 

•  $30\degree\ and\ \ 150\degree$ 

•  $90\degree\ and\ \ 90\degree$ 

Tags

CCSS.HSG.CO.C.9

Which is a counterexample to the following statement?

If an angle is obtuse, then it is $125\degree$ .

•  $90\degree$  

•  $57\degree$  

•  $160\degree$  

•  $180\degree$  

Tags

CCSS.HSG.CO.A.1

Which of the following is a counterexample to the following conjecture? If  $x^2\ =\ 4$ , then x = 2

• x = 4

• x = -2

• x = 2

• x = -4

Tags

CCSS.HSA.REI.A.2

CCSS.HSA.REI.B.4

Which is a counterexample to the following statement?

If an animal is brown, then it is a dog.

• Squirrel

• Chocolate lab

• White rabbit

• Blue jay

Which is a counterexample to the following statement?

If you add two numbers, then the sum is odd.

• 2+5=7

• 3+2=5

• 1+8=9

• 2+4=6

Tags

CCSS.7.NS.A.1

CCSS.7.NS.A.3

Which is a counterexample of: If a four sided shape has two sides the same length, then it must be a rectangle.

• quadrilateral
• rectangle
• square
• triangle

Tags

CCSS.4.G.A.2