Open Middle®
Directions: Using the values 8, 10, 12, 14, 16, 18, and 20, determine lengths for an acute triangle, a right triangle, an obtuse triangle, and a non-triangle.
Hint
For the right triangle, try a multiple of a well-known Pythagorean triple. What do you know must be true for 3 lengths to make a triangle?
Answer
Acute: multiple answers
Right: 12, 16, 20
Obtuse: multiple answers
Non-triangle: 8, 10, 18 or 8, 10, 20
Right: 12, 16, 20
Obtuse: multiple answers
Non-triangle: 8, 10, 18 or 8, 10, 20
Source: Jonathan Lees