Answer:
cos(A) = (4√97)/97
Step-by-step explanation:
The cosine is related to the sine by ...
cos(A)² = 1 - sin(A)²
cos(A)² = 1 - (9/√97)² = 1 - 81/97 = 16/97 . . . . substitute for sin(A), simplify
Make the denominator a square:
cos(A)² = (16·97)/97²
cos(A) = (4√97)/97 . . . . . square root
