In a right angled triangle, where 0 is the acute angle.
Then the side opposite to the acute angle is the perpendicular of the triangle, and the side which is adjacent to the acute angle and normal to the perpendicular is called base of the triangle.
One similarity and one difference between the definitions of can be given as:
Both the are called the trigonometric ratios, which is without any unit. The values of these both trigonometric ratios lie between -1 to 1.
is the ratio of perpendicular to the hypotenuse, but is the ratio of base to the hypotenuse.