calculator help(quick) (1 Viewer)

[cond42]

hey guys,

a bit uncertain with using degrees / radian modes on the calculator...
when do you NEED to use degree mode and when do you NEED to use radian mode

and

if there is no time when you NEED to use degree mode(not sure if there is or isnt) then can u just leave ur calc in radian mode the whole time?

thanks a heap!

 

[jet]

Radians are basically used for everything except for the angle between two lines, and if they mention that an angle is in degrees. Otherwise, radians.

 

[cond42]

ok cool thanks so i just put it back into degrees mode for trig calculations involving degrees. now just hoping i remember to!

 

[azn-drew]

the basic thing to remember:
pi(radians)=180(degrees)
then work from there,
1(radian)=180/pi(degrees)
1(degree)=pi/180(radians)
when determining what to give in your answer, ALWAYS refer to the given domain, eg. 0<x<2pi
if it gives such a condition, give your answer in radians, even if its an ugly degree. (believe me, its come up before, in which case its useful to know the above identity)
when calculating, the only time you MUST use radians is in approximation of roots and determining lengths of arcs/areas of sectors, in which case it should be a pretty small number.
common sense, pi=~3.14=180(degrees)
so, if something feels off, like you get an giant arc length or massive angle, check your calc. =]

EDIT: sorry, misread the question. i keep my calc. in degrees unless dealing with approx. roots. this is because of what i said above. xD its just a matter of remembering how many radians are degrees, eg. pi/3=60(degrees). In 3u, most questions wont get angles with crazy radian values unless dealing with arcs, sectors or root approx. =] also spelt 'above' wrong. 0_0"

 

[cond42]

ah ok i get it. so its like the only time the mode matters is when u need to find out the non-exact value(eg. not an angle like tan pi/4 which has an exact value) of a trig ratio of an angle, and u should look at the domain to figure out if the angle is in deg/rad and change ur calc mode to suit that. thanks guys i get it now(i hope im right lol)

 

[azn-drew]

not really the trig ratio of the angle but the angle itself, since the trig ratio of the angle will be the same if the angle is degrees is equivalent to the angle in radians.
but really, the only thing to worry about is to look at the given domain and make sure that you use radian values when dealing with approx. and circle stuff.
Aso, know your radian->degree conversions, eg. pi/4(radians)=45(degrees)

that should be playing it pretty safe. =]

 

[cond42]

ok thanks a heap mate, i can safely bet u saved me some marks! <3