Find the circumference of a circle given that its area is 81pi square units. Give me the answer in terms of pi AND using 3.14 as an approximation

Samantha swam upstream for some distance in one hour. she then swam downstream the same river for the same distance in only 12 minutes. if the river flows at 4 mph, how fast can samantha swim in still water?

After t seconds, a ball tossed in the air from the ground level reaches a height of h feet given by the equation h = 144t-16t^2. after how many seconds will the ball hit the ground before rebounding?

The ratio of the measures of the three angles in a triangle is 2: 9: 4. find the measures of the angels