Which three lengths could be the lengths of the sides of a triangle?

21 cm, 7 cm, 7 cm
15 cm, 5 cm, 20 cm
20 cm, 6 cm, 8 cm
9 cm, 14 cm, 22 cm

Question

Which three lengths could be the lengths of the sides of a triangle?
 	
	21 cm, 7 cm, 7 cm
	15 cm, 5 cm, 20 cm
	20 cm, 6 cm, 8 cm
	9 cm, 14 cm, 22 cm

anonymous · Answer

Read the following statement.

The figure is a triangle.

What is the first step of indirectly proving this statement?
 	
	Assume the figure is a triangle.
	Assume the figure has three sides.
	Assume the figure does not have three sides.
	Assume the figure is not a triangle.