
A rightangled triangle is a triangle in which one of the angles is a rightangle (90 degrees). The hypotenuse (h) is the longest side, which is the one opposite the right angle ($\angle{ACB}$ in the figure below). The adjacent side is the one, which is between the angle and the right angle. In the figure below, for $\angle{BAC}$, adjacent side is side AC (b). The opposite side is one not touching the angle. In the figure below, for $\angle{BAC}$, opposite side is side BC (a). In any right angled triangle : Tangent Calculator (or Tan Calculator) is an online tool which can be used to find the tangent (tan) of an angle (where angle can be in radians or degrees). It takes the value of the angle as a and calculates and displays the value of tangent of the angle, tan (a), assuming  This Calculator works for angle being in degrees as well as radians. 
Observe the give input angle. If the angle is in radians, it can be converted to degrees as follows 
Angle in degrees = $\frac{ Angle in Radians \times \pi}{180}$
Where $\pi$ = $\frac{22}{7}$ = 3.142
After that a table for conversion from angle (in degrees) to tan (tangent of the angle) has to be referred to find out the tan of the angle.