# Arccosine

vCalc Reviewed
theta =
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ID
vCalc.Arccosine
UUID
1191c841-119d-11e3-8615-bc764e049c3d

The Arc-cosine function computes the arc-cosine based on a real number between -1 and 1.

INSTRUCTIONS: Enter the following

• (x) This is the value of the cosine

Arc-cosine (θ): The arc-cosine angle is returned in degrees.  However, this can be automatically converted to radians via the pull-down menu.

#### The Math / Science

Arc-cosine is the inverse function of the cosine function. In other words if cosine(y) = x, then arccosine(x) =y.  In Right Triangles, the cosine of an angle is the ratio of the length of the adjacent side over the hypotenuses. In Vector Arithmetic, the dot product of unit vectors produces the cosine of the angle between the vectors. In both cases, the arc-cosine provides the original angle (θ).