Arccos Calculator

The arccosine function (arccos or cos⁻¹) is the inverse of the cosine function. Given a value between -1 and 1, it returns the angle whose cosine equals that value. The result is always in the range [0°, 180°] or [0, π] radians.

1. Enter a value between -1 and 1
2. Select DEG to see result in degrees, or RAD for radians
3. The angle is calculated automatically
4. Both degree and radian values are shown

• Calculate inverse cosine for any valid value
• Results in both degrees and radians
• Input validation for domain [-1, 1]
• Shows verification: cos(result) = input
• Real-time calculation

Why is arccos range [0°, 180°] different from arcsin?

Each inverse trig function has a specific range to ensure it returns a unique value. For arccos, the range [0°, 180°] covers all possible cosine values exactly once.

What is arccos(0)?

arccos(0) = 90° or π/2 radians. This means cos(90°) = 0.

What is arccos(-1)?

arccos(-1) = 180° or π radians. This is the maximum angle returned by arccos.