The expression you’re looking at, tan a tan 60 a, can be evaluated by using the known value of tan 60°.
We know that:
tan 60° = √3
So, if we rewrite the expression, we have:
tan a * tan 60° = tan a * √3
Thus, the expression tan a tan 60 a simplifies to tan a * √3.
This means that the answer to the question is dependent on the value of tan a which you might have to calculate or be given.
In conclusion, tan a tan 60 a = tan a * √3.