So I understand rads is they are in the form of x*PI / y

That is pi/3 = 60 degrees.

My book sometimes just has "4.7". There is no degree sign, so assume this is rad.

4.7 what? 4.7 times 2pi? 4.7 pi?

How many degrees is 4.7? In terms of pi, how many rads?

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Converting to degrees from radians --> multiply by 180/pi

Assuming 4.7 is in radians (which it sounds like it is), that would equat to roughly 269 degrees because 4.7 * (180 / pi) = 269.290164.

Say you're trying to find something--for example, the degree measurement of a angle given in radians. Let's say 4.7 radians. What's that in degrees?

If you look at my conversion factor above, to go to degrees from radians to multiply by 180/pi. In this sense, 180 is a measure of degrees and its equivalent is a measure of radians (because pi radians is 180 degrees, right?). You started off with radians and when you multiply by degrees/radians you should get degrees. If you don't, something's wrong.

(radians / 1) * (degrees / radians) = degrees

You divide radians by radians to get 1 and you're left with degrees.

Dimensional analysis is a little extra step to make sure you're not crazy and your formula is correct.

So your 4.7 is just 4.7 radians, convert as you normally would. Given that you know 360 degrees = 2pi radians, 1 radian = 180/pi degrees

japanonAlso, something I tripped up on when I was in school, Pi is not a unit of measurement. So it's not 2.3 "pi-radians" Pi is just a (extremely helpful) constant. So 2.3pi radians. Replace pi with any other constant. Pi is just seen all the time because it makes the unit circle come out even.

It is not.

When you have "5m" you know you're talking about a length. "X radians" or "Y degrees" is not a dimension, it is a pure ratio. Meters per meters = m / m = dimensionless.

The reason we need to distinguish them is because we have two conventions for representing the angle, radians and degrees, and 3 radians is very much different from 3 degrees, so the number alone isn't always enough. (Most of the time it is implied though.)

RhinoonHow do you subtract 4.7 from 3pi/2 without rounding? Book/online says exact answer in terms of pi.

3pi/2 - 4.7 =

3pi/2 - 9.4/2 =

(3pi)-9.4 /2 =

how do reduce? online course doesn't accept that answer. Says it needs to be a reduce fraction in terms of pi (says, error: not simplified).

If i convert/round to decimal it says to give exact answer in terms of pi (says: error: needs to be a reduced fraction in terms of pi)

edit: for decimal I get apox: 0.01238898038468985769396507491925

Is that part right at least?

RhinoonVeeveeon