# Excel ASIN Function

The Excel ASIN function returns the angle of a right triangle given the ratio of its adjacent side over its hypotenuse side. ASIN is the inverse of the SIN function.

**number**- The ratio of the opposite-side over the hypotenuse of a right-triangle.

The ASIN function returns the angle of a right triangle given the ratio of the adjacent side over the hypotenuse side. The input number must be between -1 and 1. For example, if the length of a right-triangle's adjacent side is 1 and the length of its hypotenuse is 2 to find the angle of the triangle the formula is:

=ACOS(1/2) // Returns 0.524 radians

To convert the result from radians to degrees, the formula is:

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