It is, indeed, the same way the natural logarithm is natural. :-)
The two trigonometric functions cosine and sine can be defined in a pure analytical sense as the solutions to the differential equation d²y/dx² = -y through the line elements (0,1;0) and (0,0;1), respectively. The unit automatically becomes radians.
The two trigonometric functions cosine and sine can be defined in a pure analytical sense as the solutions to the differential equation d²y/dx² = -y through the line elements (0,1;0) and (0,0;1), respectively. The unit automatically becomes radians.