To the nearest tent what is the area of circle whose diameter is 21 inches

It depends

Step-by-step explanation:

Area of a circle is given by

A = pi *r^2

We can find the radius by taking 1/2 of the diameter

r= 1/2(21)

r = 10.5

A = pi * (10.5)^2

A = 110.25 pi

Approximating pi with 3.14

A = 110.25 * 3.14

A =346.185 in^2

To the nearest tenth

A = 346.2 in^2

If we use the pi button on the calculator

A = 346.3605901

Rounding to the nearest tenth

A = 346.4 in^2

You need to determine whether you approximate pi by 3.14 or use the pi button on your calculator

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240