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
Use <, =,  or > to compare the following sums:
$\frac12 + \frac14$  ________  $\frac13 + \frac15$
$\frac13 + \frac12$  ________  $\frac13 + \frac14$


aligns: no