If sin  calculate Cos A and tan A

Let ΔABC be a right-angled triangle, right-angled at point B

Given that:

As we know trigonometrical ratios give ratio between sides of right angled triangle instead of their actual values. So from sin A we get the ratio of Perpendicular and Hypotenuse of the triangle. Now as we don't know the exact value let Perpendicular = 3 k and Hypotenuse = 4 k

According to Pythagoras theorem: (Hypotenuse)² = (Base)² + (Perpendicular)²

Applying Pythagoras theorem in ΔABC, we obtain

AC² = AB² + BC²

(4k)² = AB² + (3k)²

16k² - 9k² = AB²

7k² = AB²

Cos A =

= =

And we know that 

Tan A =

= =

So the ratios are cos A = √7/4 and tan A = 3/√7