Do you use degrees or radians for trig functions?

Question

I was just wondering if you use degrees or radians in trig functions. For example if I have a degree of 0.5 would I do: Sin(0.5) or would I have to convert that to radians?

Or does it not matter either way?

Answer 1

I am not 100% sure that I understand what you are asking.

But, I think the answer is: it doesn't matter. You can find the value of any trigonometric function at an angle measured in radians or in degrees. So, for example, you would have $$ \sin(45^\circ) = \sin\left(\frac{\pi}{4}\right) = \frac{\sqrt{2}}{2}. $$ Note here that one often adds the degree symbol ${}^\circ$ to indicate when you are using degrees. So if you are evaluating a trigonometric function at a number without this symbol, then I would assume that it is in radians.

Even though you can use both, often people will insist on using radians for trigonometric functions. And often radians is assumed by default. If you for example google "sin(90)" you get $0.893...$ because Google assumes that it is $90$ radians and not $90$ degrees.

If you are using in calculator, you often have the option of of using one or the other. But you have to change the "mode" on the calculator.