Home >> Science & Nature >> Science

How to Do Inverse Trigonometry

Trigonometry is the study of triangles, and their associated angles and lengths. There are three main trigonometric functions -- sine (sin), cosine (cos) and tangent (tan). The functions are generally used to find the length of a triangle side when given the length of another side and an angle. The inverse trigonometric function can determination the triangle angle given the length of two sides.

Things You'll Need

Scientific calculator

Instructions

- 1
  Draw the triangle and label each side with their lengths. Label the unknown angle with a "theta" symbol (Θ).
- 2
  Perform inverse trigonometry to find the unknown angle. If all three sides of the triangle are known, then any of the inverse trigonometric equations may be used. The trigonometric equations are:
  
  ArcSin (opposite / hypotonuse) = theta
  
  ArcCos (adjacent / hypotonuse) = theta
  
  ArcTan (opposite / adjacent) = theta
- 3
  Type the problem into the calculator. For example, if the angle opposite the unknown angle is 5cm, and the angle adjacent to the unknown angle is 3cm, type the following into the calculator:
  
  5 / 3
  
  Next, press the "ArcTan" button. The unknown angle will now be displayed on the calculator display.

Science