Answer:53.78
Explanation:
a^2 = b^2 + c^2 - 2bc cos A
a=18
b=10
c=22
18^2= 10^2 + 22^2 - 2* 10 * 22 cos A
324= 584 - 440 cos A
-260=-440 cos A
cos A=53.78
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