Find the area of a regular octagon with a side length of 12cm.

Steps:

Shape: Regular octagon

Solved for area

Side length= 12cm

A=2(1+√2)a2

Description:

Using the formula A=2(1+√2)a2 for area and  Regular octagon, we calculate the side length that is 12 cm. After you calculate your answer will equal as A≈695.29cm². Since it says to round to the tenth, your answer will equal as 695.3 after rounding.

A≈695.29cm²

Round to the nearest tenth =  695.3

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Hope this helps.

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15