A calculator can be used to calculate the size of an angle using an inverse trigonometric function if the lengths of the two line segments forming the angle are known, according to RegentsPrep.org. The formula for the number of radians in an angle is arccosine(adjacent side length/hypotenuse length).
Continue ReadingFinding the dimensions of an angle numerically requires that some basic information be known about the angle, or the two line segments or rays which compose it. The simplest method is to use lengths of two sides forming the angle, and then calculate the dimension using the inverse cosine function. The inverse cosine function takes as input the two side lengths for the line segments of which the angle is composed. Other, more difficult functions require the addition of another line segment to solve the problem with a calculator.
Obtaining the side lengths manually can present a problem, as empirical measurement accuracy can introduce large errors into calculated solutions. Special care must be taken when constructing a triangle from an angle to ensure one of the two line segments adjacent to the angle to be measured is the longest side of the triangle. If the inverse cosine function is used, the length of the third side is not needed to solve the problem.
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