If sin α = 12/13 , and cosα = 5/13 , then tanα =?
it would be great if you could add a few words of explanation

If you draw a right angles triangle you can fill in the values. So since sinx= opposite/hypotenuse then the hypotenuse of the triangle is 13. And the side opposite the angle a is 12. Since cosx= adjacent/ hypotenuse, the adjacent side is 5.
Tanx=opposite/adjacent and therefore tana= 12/5