Aas i belive . If not consult the other answer
The polygon in option 3 is not octagon at all, it is heptagon (or 7-sided polygon).
A convex octagon has no angles pointing inwards. More precisely, no internal angles can be more than 180°.
When some internal angle is greater than 180°, it is concave.
In option 2 you can see that one angle is pointing inward, then this octagon is concave.
Answer: correct choice is B.
Answer: Second option.
Step-by-step explanation:
You need to use the following formula:

Where "B" is the area of its base and "h" is the height.
According to the data given in the exercise, you know that:

Therefore, knowing this values, you can substitute them into the formula shown before and then evaluate, in order to calculate the volume of thi right pyramid whose base is a regular hexagon.
Then, you get:

Answer:
-1
Step-by-step explanation:
Square root 1 is 1. Add that to the 12 to get 13. Subtract 13 from both sides to get: -5x = 5. Divide both sides by -5 to get your answer: -1