When do you use Deg, Rad and Gra and what do they mean?

Deg, Rad and Gra are three angle modes on scientific calculators. Beginners don’t usually know the use of them nor their definition.  They are very simple to understand and also to use when being explained briefly and as simple as possible.

On a scientific calculator “D” or “DEG” means the current angle mode is in degrees. A degree is a complete revolution of 360 or you could say it is 1/360 of the circumference of a circle. One degree is represented as 1⁰.

E.g. – sin90⁰=1

Another is “R” or “RAD”; it means the current angle mode is in Radian. A radian had to deal with pi). This is a short cut symbol; π numerically means 3.14 or 22/7. Measurements of angles using radian are called the “radian system of angular measurements.” It is 1/2πr of the circumference of a circle.

E.g. – sin (π/2) =1

The last one is “G” or “GRA”; it means the current angle mode is in Grad. A grad is 1/400 of the circumference of a circle.

E.g. – sin 100 grads= cos 400 grads =1

Degree is the default angle mode on a programmable/scientific calculator. If there is a degree sign after the angle, the trig function evaluates its parameter as a degree measurement, if not, the trig function evaluates it parameter as a radian measurement because radian measurements are considered to be “natural” measurements for angles.

All these three modes are basically used to find angles, especially when doing trigonometry.