Question

Finding the Sum of Exterior Angles
Cody drew in the 3 exterior angles of his triangle. He measured each angle and labeled them below.

A triangle has exterior angles 135 degrees and 100 degrees. An angle with 145 degrees is not an exterior angle.

Cody found the sum of the exterior angles to be 380°. Did Cody make an error? If so describe it.
No, Cody did not make an error. The sum of the exterior angles of a triangle should be 380°.
Yes, Cody made an error adding the three exterior angles together.
Yes, Cody made an error drawing the exterior angles. The 145° angle is not an exterior angle.
Yes, Cody made an error drawing the exterior angles. The 100° angle is not an exterior angle.

Answer 1

Yes — Cody made an error drawing the exterior angles. The sum of one exterior angle at each vertex of any triangle is 360°, not 380°. If two exterior angles are 135° and 100°, the third must be 360 − (135 + 100) = 125°, so the 145° label is not an exterior angle.