I am going to assume that this pond is a perfect circle, because you said to use pi and find a radius.
The area of a circle is given by the formula
A = pi *r^^2. (Using * for multiplication and ^^ to indicate an exponent)
you are given A, the area, as 78.5 yards. Pi is a constant. You need to plug-in the area and solve for r, the radius. So
78.5 = pi * r^^2 ...divide both sides by pi
78.5 / pi = r^^2 ... now take the square root of both sides to get your answer.
sqrt(78.5/pi) = r Use your calculator to find the answer. I would round to the nearest tenth unless your teacher asked for something else.
