1. consider one angle of a (convex) heptagon. From that angle you can construct 7-3=4 diagonals. (-3 because we cannot create diagonals with the adjacent vertices and the angle itself )
2. 4 diagonals create 5 triangular regions. (check the picture)
3. So the sum of the measures of the interior angles of the heptagon is 180°*5=900°.
4. The measure of the remaining 7th interior angle is 900°-(120+150+135+170+90+125)°=110°.
5. The largest exterior angle is when the interior angle is the smallest.
6. The smallest interior angle is 90°, so the largest exterior angle is 180°-90°=90°
Answer: 90°
2. 4 diagonals create 5 triangular regions. (check the picture)
3. So the sum of the measures of the interior angles of the heptagon is 180°*5=900°.
4. The measure of the remaining 7th interior angle is 900°-(120+150+135+170+90+125)°=110°.
5. The largest exterior angle is when the interior angle is the smallest.
6. The smallest interior angle is 90°, so the largest exterior angle is 180°-90°=90°
Answer: 90°