Trig? TRIG! TRIIGGGG!

Bucketman

Ok, I normally don't ask about homework in here, but this is about to make me explode.

So I'm in basic Trig this semester, and its near the end. Pretty easy stuff, but this drives me nuts.

I need to convert an angle from degrees to radians. I have 300 degrees.

I know its just 300x(pi/180) BUT it wants to answer in respect to pi. My book gives me no clues how to do this and I can't figure it out. For instance the example in the book is 270 degrees, and the answer is 3pi/2. When I do it I get 4.712. Which the stupid online math program would say is wrong.

For the 300 degree problem I tried putting in 5.236 but it will only accept it in respoect to pi. PLEASE HELP. I have about 8 problems like this and I can't figure it out.

FirstComradeStalin

Respect to pi just means you never break pi down into 3.14etc. So 300 degrees with respect to pi is just 300/180*pi=5/3*pi

Bucketman

Well thanks, though I think I'm still a little confused.

musanman

Pi = 180 degrees.

270 / 180 * pi = 3/2 * pi (reduce the fraction).

FirstComradeStalin

Basically they're asking "How many pis is this?" 180 degrees = 1 pi radians, so you do everything in respect to that proportion.

Bucketman

OH! Ok, now I see! Thank you. I was just doing the math instead of reducing it down.

tarnok

I feel compelled to point out that reducing it _is_ doing the math. Anything other than that does not give you the actual answer but an approximation of the correct number. There is actually no way to write (5/3)pi as a decimal unless you have an infinite amount of paper and time. Like three, or two, (5/3)pi is the proper name for some number; it is the simplest possible way of writing that number.

FirstComradeStalin

I get the feeling Bucketman's problem was a slavish dedication to his calculator instead of trying to work it out on paper/in his head. That's really the point of getting answers with respect to pi, so you don't have to use a calculator

BoomShake

FirstComradeStalin wrote: »

I get the feeling Bucketman's problem was a slavish dedication to his calculator instead of trying to work it out on paper/in his head. That's really the point of getting answers with respect to pi, so you don't have to use a calculator

No, the point of getting things with respect to Pi is that it's significantly more useful if, and more likely when, you want to use it further. This is both because of the error introduced by simplifying and because Pi's sometimes cancel later on. Pi simply becomes a "unit for the unitless", used just like meter or second.

tarnok

BoomShake wrote: »

FirstComradeStalin wrote: »

I get the feeling Bucketman's problem was a slavish dedication to his calculator instead of trying to work it out on paper/in his head. That's really the point of getting answers with respect to pi, so you don't have to use a calculator

No, the point of getting things with respect to Pi is that it's significantly more useful if, and more likely when, you want to use it further. This is both because of the error introduced by simplifying and because Pi's sometimes cancel later on. Pi simply becomes a "unit for the unitless", used just like meter or second.

As a teacher I can't tell you how many students I've seen befuddled by a problem because they end up with decimals out to five or six places when it would have taken about three seconds to solve the problem with fractions.

If anyone reading this is still taking math classes the best thing you can do for yourself is to stop using a calculator right now except on tests.

psyck0

Yup, we weren't allowed calculators in high school for that very reason, and it paid off both in University and in "real life".

Delzhand

I never did very well in trigonometry until I started using it for game programming. When you're trying to figure out what the velocity of a bullet fired at X angle is, suddenly degrees become a lot less helpful.

Of course, on a test you can't write MathHelper.ToRadians(300)...