Find the area of equilateral triangle

3·1/2·4^2·SIN(1/3·360°) = 20.78

 The required area of the given equilateral triangle is 20.78 ft².

Step-by-step explanation:  We are given to find the area of the equilateral triangle shown in the figure.

We know that the area of an equilateral triangle having radius of circumscribed circle equal to r units is given by

For the given equilateral triangle, we have

r = 4 ft.

Therefore, the area of the given equilateral triangle is

Thus, the required area of the given equilateral triangle is 20.78 ft².

step-by-step explanation:

cats

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