why do so many calculators have different answers to "19(cos(38))"?

Question

i tried six identical calculators and most said ≈14.97, but one said 18.14. google says 18.14, microsoft calculator says 14.97, desmos scientific says 14.97, desmos graph calculator says 18.14, wolfram alpha says 14.97.

i have tried many different variations, like

19cos38

19(cos38)

19(cos(38))

19cos(38)

19*cos*38

19*(cos*38)

19(cos*38)

19*(cos38)

19*cos*(38)

19*cos(38)

19(cos*(38))

(19)cos38

(19)cos(38)

(19)cos*38

(19)cos*(38)

(19)(cos38)

(19)(cos(38))

(19)(cos*38)

(19)(cos*(38))

(19)*cos38

(19)*cos(38)

(19)*cos*38

(19)*cos*(38)

(19)*(cos38)

(19)*(cos(38))

(19)*(cos*38)

(19)*(cos*(38))

you get the gist of it. of course, i did not try all of them, but many. i probably also broke every rule in this post lmao

1. "Keep your questions short and to the point
2. Check for grammar or spelling errors
3. Phrase it like a question

but, anyway, does anyone have answers of which one may be able to answer the question as to why this happens?

Answer 1

Actually, this is pretty simple to answer. Check if your calculator defaults to degrees or radians. My calculator defaults to degrees, but has a "drg" key that lets you select degrees, radians or grads.

19cos(38°) ≈ 14.97

19cos(38 radians) ≈ 18.14

Notice that Wolfram alpha gives you a choice:

"Assuming trigonometric arguments in degrees | Use radians instead"

Answer 2

cos38 = 0.78801... when 38 means 38 degrees

cos(38 radians) = cos(38-37.7 radians) = about cos(.3 radians)

=about cos(17.2 degrees)= about .955

convert 38 radians to degrees 38 x 180/pi = about 38(180)/3.14159 = about 2,177 degrees

subtract 360x6 = 2160. 2177-2160 = 17 degrees. cos17 = about .956. .956x19 = about 18.2

19 x .95 = about 18.1

19 x .788 = about 15

since cosines are less than or equal to 1

you know 19cosine of any angle will be less than or equal to 19

at least you know about 15 and 18 are in the right range for the answer

if you got anything over 19 or under -19, you know there's a mistake somewhere