sin 0 = 2/7, cos 0 =3 sq root 5 / 7 What is Tan?

If you know the sine value and the cosine value, you can find the tangent value by using this formula:

     tan(x)  =  sin(x) / cos(x)

So:  tan(x)  =  [2/7] / [3√5/7]  

Multiply both the numerator and the denominator by 7:  tan(x)  =  2 / (3√5)

If you need to, you can rationalize the denominator.