Please explain how to do this

Option 4

Step-by-step explanation:

Area of a circle (A) = πr²(i)

Circumference (C) = 2πr

=>C = 2πr

=> 2πr= C

=> π = C/2r

Substituting the value of π = C/2r in the first equation i.e (i)

A = (C×r²)/2r

= (C . r)/2

= 1/2 × C × r

Therefore, option 4 is the correct option

whole numbers.

step-by-step explanation:

we are given the average monthly rainfall (in millimeters) model r(m) for the years 1900-2009 as a function of the month number m.

as we can see m is taken for the number of months for years 1900-2009.

we know that number of months can't be a negative number or decimal number or a fraction.

so, the number of months could be only positive whole numbers.

therefore, whole numbers is more appropriate for the domain of r.

30 feet

step-by-step explanation:

that would be 2 1/2 * 12

= 24 + 6

= 30 feet   (answer)