A regular hexagon is inscribed in a circle with radius 9 cm. Find the area

121.5sqrt(3)

Step-by-step explanation:

Ok, so all regular hexagons are made out of 6 equilateral triangles. If the hexagon is inscribed in the circle, the radius lines up with a side of one of the 6 equilateral triangles and you get 6 equilateral triangles with a side length of 9.

The formula for an equilateral triangle's area is (a/2)^2 * sqrt(3) where a = side length. That means we just plug in 9 to find the area of one of these six triangles. We get 20.25sqrt(3).

We multiply this by 6 (to find the sum of the areas of 6 equilateral triangles) and get 121.5sqrt(3)

expression #3 is not equivalent. the others are.

all but the second one

step-by-step explanation:

cuz that one goes over 180

mark brainliest