Geometry and TrigonometryEasy–MediumAngle sum of an octagon
Geometry and Trigonometry practice question
What is the sum, in degrees, of the interior angles of an octagon?
Answer: 1080
An n-sided polygon has interior angle sum (n − 2) × 180. For n = 8: 6 × 180 = 1,080.
Common wrong answers
- If you answered 135
- 135 is ONE interior angle of a regular octagon, not the sum.
- If you answered 360
- 360 is the sum of the EXTERIOR angles of any polygon.
- If you answered 1440
- 1,440 uses 8 × 180, forgetting to subtract 2 from the number of sides.
More Geometry and Trigonometry questions
- Easy–Medium
A circle has a radius of 6. What is its area? (Use A = πr².) - Easy–Medium
A right triangle has legs of length 6 and 8. What is the length of the hypotenuse? - Easy–Medium
A circle has a radius of 5. What is its circumference? (Use C = 2πr.) - Easy–Medium
What is the midpoint of the segment joining the points (2, 3) and (8, 11)? - Easy–Medium
What is the measure, in degrees, of angle B? - Easy–Medium
What is the area, in square centimeters, of the trapezoid?
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