The area of a circle varies directly with the square of its radius. if the area 4πcm² when the radius is 2cm, find the area when the radius is 3cm

A = 9π cm²

Step-by-step explanation:

Given that area (A) varies directly with r² then the equation relating them is

A = kr² ← k is the constant of variation

To find k use the condition A = 4π when r = 2 , then

4π = k × 2² = 4k ( divide both sides by 4 )

π = k

A = πr² ← equation

when r = 3 , then

A = π × 3² = 9π cm²

i think it is everything has to equal 180 so, if i correct 4=c. 6=d. 8=a. 7=b. and the last question would be c. because they are parallel lines and they are congruent.

step-by-step explanation:

the reason everything has to equal to 180 is because that is how it works. i'm guessing that is its rule. 4 and 8 are congruent and parallel so, that would be 30+30 because they have the same number. it would equal 60. 6 and 7 are congruent and parallel so, that would be 30+30 because they have the same number. it would equal 60. 60+60 is 180. so, now you have your answer