Step-by-step explanation:
[tex]49 = {r}^{2} \\ \: \: \: \: \: \: r = \sqrt{49} \\ \: \: \: \: \: \: r = 7 \: cm[/tex]
The diameter is twice the radius of the circle
diameter
= 2 x r
= 2 x 7
= 14 cm