Question

You are asked to draw a triangle using three of the following angles: 0°, 30°, 45°, 55°, 60°, 80°, 90°, 105°. Which triangle cannot exist?

Answer 1

well the angle sum of a triangle has to be 180 degrees... anything less isn't a closed shape, anything larger isn't a triangle...

so to start you can eliminate and triangle with an angle 0

then look at combinations that sum to more than 180 and less than 180. these can be eliminated.

you need to know you can't have a triangle with 2 angles larger than 90...

so that may help you eliminate a lot of possibilities