# Bug in cos function in version 7.2

I have 'SageMath version 7.2, Release Date: 2016-05-15' and when I enter `cos(pi*(1+(5/63)))`

it returns `cos(5/63*pi)`

which is incorrect (there should be a negative sign in front). Entering `cos(N(pi)*(1+(5/63)))`

returns `-0.969077286229078`

which is correct, but entering `N(cos(pi\*(1+(5/63))))`

returns `0.969077286229078`

. Similar things happen when `5/63`

is replaced with other fractions, but not always. Usually if the fraction is "nice", like `1/4`

or `1/5`

then it seems to get the right answer. I assume this has something to do with the exact answer being able to be expressed nicely with square roots, but I don't really know. Same happens with `sin`

as far as I can tell. Anybody else having this problem?