The value of tan a is 2.9098
Explanation:
The given value is 
Now, we shall find the value of sin (a), using the identity,

Substituting the value of cos (a), we get,

Subtracting both sides by 0.1056, we have,

Taking square root on both sides, we get,

Now, we shall substitute the value of sin (a) and cos (a) to determine the value of tan (a) in the identity 

Thus, the value of tan (a) is 2.9098