sen(a/2)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
meio ângulo
About this calculator
The sen(a/2) calculator is a useful online tool for calculating the sine of an angle given, divided by 2. Based on the formula sen(a/2) = ±√((1−cos a)/2), you can easily calculate the value of the sine of a half angle.
This calculator is especially useful for advanced trigonometry problems, where it is necessary to calculate sines and cosines of half angles. With this tool, you can save time and avoid calculation errors.
Please note that this calculator assumes the angle a is in radians. If your problem is in degrees, make sure to convert the angle before using this calculator.
Also, be aware that the formula sen(a/2) = ±√((1−cos a)/2) produces two possible results for each angle, depending on the sign of the sine of the angle. Be sure to consider both cases when necessary.
Frequently asked questions
What angle a should I use in this calculator?
The angle a should be in radians. If your problem is in degrees, make sure to convert the angle before using this calculator.
Why am I seeing two possible results for the sine of an angle?
This occurs because the formula sen(a/2) = ±√((1−cos a)/2) produces two possible results for each angle, depending on the sign of the sine of the angle.
Can I use this calculator to calculate cosines of half angles?
Yes, you can use this calculator to calculate cosines of half angles. Just use the formula cos(a/2) = ±√((1+cos a)/2).
When should I use this calculator?
This calculator is especially useful for advanced trigonometry problems, where it is necessary to calculate sines and cosines of half angles.