Question

The Impossible Triangle

Which of these three triangles is impossible to draw? Explain.

You may use the Three Angles applet to test your thinking.

1. A triangle where one angle measures 20° and another angle

measures 45º. 115

2. A triangle where one angle measures 120° and another angle

measures 50°

3. A triangle where one angle measures 90° and another angle

measures 1000

END

Summary

Answer 1

Answer: Triangle 3

Explanation:

The angle measures have to add to 180 degrees, so triangle 3 is impossible as it already exceeds this sum with the 2 given angles.