MathematicsTrigonometry
Arcsin Calculator
Calculate inverse sine (arcsin) values instantly. Enter any value between -1 and 1 to find the corresponding angle in degrees or radians. Free arcsin calculator.
The arccos calculator helps you find the inverse cosine of any number between -1 and 1. Also known as arccosine or cos⁻¹, this trigonometric function returns the angle whose cosine equals your input value. Whether you're working in degrees, radians, or other angular units, this calculator provides instant, accurate results for mathematics, physics, and engineering applications.
Arccos (inverse cosine) is a trigonometric function that reverses the cosine operation. If cos(θ) = x, then arccos(x) = θ. The function accepts input values from -1 to 1 and returns angles between 0 and π radians (0° to 180°). This range represents the principal values of the inverse cosine function.
In mathematical notation, arccos is written as cos⁻¹(x) or acos(x). The function is commonly used in geometry to find angles in triangles when side lengths are known, in physics for wave analysis, and in computer graphics for calculating viewing angles and rotations.
Using the calculator is straightforward. Enter your known value in either field. If you know the x value (between -1 and 1), enter it to calculate the corresponding angle. If you know the angle, enter it to find the cosine value. Select your preferred angle unit from the dropdown menu—degrees, radians, gradians, or turns. The calculator automatically updates results as you type.
Arccos appears frequently in triangle geometry, where it helps determine angles from side ratios. In physics, it's used to analyze periodic motion, wave interference, and vector projections. Computer graphics rely on arccos for lighting calculations, camera angles, and 3D rotations. Navigation systems use it to calculate bearing angles, and in engineering, it helps with structural analysis and signal processing.
Remember that arccos only accepts values between -1 and 1 inclusive
The output angle will always be between 0° and 180° (0 and π radians)
Use radians for calculus and advanced mathematics, degrees for everyday applications
Common values: arccos(1) = 0°, arccos(0) = 90°, arccos(-1) = 180°
What is the domain of arccos?
The domain of arccos is [-1, 1]. Any input outside this range is undefined because cosine values cannot exceed these bounds.
Is arccos the same as 1/cos(x)?
No. The notation cos⁻¹(x) means inverse cosine (arccos), not 1/cos(x). The reciprocal of cosine is called secant, written as sec(x).
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