In this case, we'll have to carry out several steps to find the solution. 
Step 01:
Data
radius = √98
center = (5.9,6.7)
equation of the circle = ? 
Step 02:
Equation of the circle
(x - a) ² + (y - b) ² = r ² 
(a , b) = center 
(x - 5.9) ² + (y - 6.7) ² = (√98) ² 
(x - 5.9) ² + (y - 6.7) ² = 98 
The answer is:
(x - 5.9) ² + (y - 6.7) ² = 98