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
A spider walks on the outside of a box from point A to B to C to D and finally to point E as shown in the picture below.
[IMG]
Draw a net of the box and map out the path of the spider on the net.
Compare your net with those of some other people.
Cut out the net and put the box together to see if you are right.
How long is the path of the spider?


aligns: no