13. Find the area of a circle with a
circumference of 26 (pi)feet.
16. Find the circumference of a
circle with an area of 289(pi)mm2.
17. Find the circumference of a
circle with an area of 113.1 in 2
18. Find the area of a circle with a
circumference of 131.95 meters.

13. 169π ft²

16. 34π mm

17. 12π in

18. 441π m²

Step-by-step explanation:

Circumference of a circle is calculated as follows:

C = 2π*r

Area of a circle is calculated as follows:

A = π*r²

where r is the radius of the circle

13. circumference of the circle: 26π ft

Then, its radius is:

26π = 2π*r

r = 26π/(2π) = 13 ft

A = π*13² = 169π ft²

16. area of the circle: 289π mm²

Then, its radius is:

289π = π*r²

r = √289

r = 17 mm

C = 2π*17 = 34π mm

17. area of the circle: 113.1 in²

Then, its radius is:

113.1 = π*r²

r = √(113.1/π)

r = 6 in

C = 2π*6 =  12π in

18. circumference of the circle: 131.95 m

Then, its radius is:

131.95 = 2π*r

r = 131.95/(2π)

r = 21 m

A = π*21² = 441π m²

the solution of the equation is 2.23 ⇒ answer b

step-by-step explanation:

* lets revise the meaning of exponential function

- the form of the exponential function is y = ab^x, where a ≠ 0, b > 0 ,  

  b ≠ 1, and x is any real number

- it has a constant base b

- it has a variable exponent x

- to solve an exponential equation, take the log or ln of both sides,  

  and solve for the variable

* lets solve the problem

∵

- the base is 7 and the exponent is x

- insert ㏑ in both sides

∴

- use the rule

∴ x ㏑(7) = ㏑(77)

- to find x divide both sides by ㏑(7)

∴

* the solution of the equation is 2.23 to the nearest 2 decimal places

it would rotate about 180 degrees.