standard_description: Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles. For example, arrange three copies of the same triangle so that the sum of the three angles appears to form a line, and give an argument in terms of transversals why this is so.
problem_activity: Task
The goal of this task is to estimate the measure of angles in triangles with integer side lengths.
What are the angle measures in a triangle whose three sides each have length of one unit?  Explain.
What are the approximate measures of the three angles in a triangle whose side lengths are 3, 4, and 5 units respectively? Explain.
What are the approximate angle measures of the three angles in a triangle whose side lengths are 2, 3, and 4 units respectively?


aligns: no