Answer :

A=πr^2.
49
π=πr^2
49=r^2
7=r
d=2r
d=2(7)
d=14
Please allow me to use area of circle as = πd^2 / 4

Therefore  πd^2 / 4  =   49π      Cancel out π from both sides.

d^2 / 4  =   49      Cross Multiply

d^2   =   4*49

d^2   =   196      Take the square root of both sides

d  =  √196            Use your calculator

d  = 14

Hence, diameter of the circle is 14 units.
Cheers.