"Find the area and the circumference of a circle with diameter of 8m"

Radius = diameter/2 = 8/2 = 4m

Area of a circle = pi x r^2 = pi x 4^2 = 16pi m^2 ( exact area) or 50.27 m^2

Circumference = pi x diameter = 8pi m ( exact) or 25.12 m

C = 25.12 A = 50.24

Step-by-step explanation:

Circumference formula = dπ

Area formula = πr^2

Circumference:

Plug in:

8π

8 × 3.14 = 25.12

Area:

8/2 = 4

r = 4

Plug in:

πr^2

π4^2

16π

16 × 3.14 = 50.24

Hope this helped.

step-by-step explanation: a reaction is first order. if the initial reactant concentration is 0.0200 m, and 25.0 days later the concentration is 6.25 x 10-4 m, then its half-life is:

$9.89

step-by-step explanation:

9.90 = p x .06 x .25 (3/12 changed to a decimal)

9.90 = p x 0.015

9.90 - 0.015 = p

9.89 = p