completley lost (math b)

[WEEGEE SEE ALL]

my teacher through me to the dogs. i have NO math b knowledge. but my teacher gave me these 3 problems because i was doing "too good" in math a.these are all all or nothing if i dont get these 3 its an automatic fail. hes counting it as a test and project which is 50% of the grade together.


1. is 1/2 sin 2x the same expression as sin x? justify your answer (i dont even know where to start)

2. a ball is rolling in a circular path that has a radius of 10 inches. what distance has the ball rolled when the subtended arc is 54 degrees.express you answer to the nearest hundredth of an inch( i only know what a subtended arc is because the booklet has a diagram. since its a radius i know both lines are 10 inches and the inside angle is also 54 degrees.in the end thats all useless knowledge because that doesnt help me change that degree to inches(also i cant explain how i know that inside angle is also 54 i just know)

3.a set of normally distributed student test scores has a mean of 80 and a standard deviation of 4. determine the probability that a randomly selected score will be in between 74 and 82.(im lost on this too. i dont know what a deviation is and i dont know exactly what they want me to figure out since they didnt give me a number of people)


im not expecting an answer from anyone just an explanation of what i have to do. in the end i need to explain how i solved this so the explanation is somewhat more important than the answer. im in a catch the fish or teach the man to fish situation

 

[fasteddie65]

1. is 1/2 sin 2x the same expression as sin x? justify your answer (i dont even know where to start)

Do you remember the identity for sin 2x? sin 2x = 2 sin x cos x.

So is (1/2) sin 2x the same as sin x?

BTW, use parentheses around fractions.

 

[fasteddie65]

2. a ball is rolling in a circular path that has a radius of 10 inches. what distance has the ball rolled when the subtended arc is 54 degrees.

Do you know how many degrees there are in one complete revolution? 360°

54° is what fraction of that?

Find the circumference of the ball, which would be the distance rolled in one revolution, then multiply by that fraction.

 

[Loren]

If you can't answer yes or no to #1, I suggest you select a value for x, say 20°. Then find the sin of 20°. Then find the sin of 40° and take half of it. Then compare results. At least you will be able to say yes or no.

 

[Deleted member 4993]

im not expecting an answer from anyone just an explanation of what i have to do. in the end i need to explain how i solved this so the explanation is somewhat more important than the answer. im in a catch the fish or teach the man to fish situation

The best way to learn to catch "mathematical" fish - is to open the book and do the example problems of the chapter. Then come to us with work and indicating exactly where you are stuck. If you don't tell us that - we may have to assume you don't know where the river bank is - and your catching fish will be delayed.

In other words - if you really want to learn - show us some work.

 

[WEEGEE SEE ALL]

2. a ball is rolling in a circular path that has a radius of 10 inches. what distance has the ball rolled when the subtended arc is 54 degrees.

Do you know how many degrees there are in one complete revolution? 360°

54° is what fraction of that?

Find the circumference of the ball, which would be the distance rolled in one revolution, then multiply by that fraction.

so what i think what your saying is find out what percent 54 is of 360 right?
i dont think i know how to solve the circumference.would getting the diameter calling that 100% and then converting what the 54 degrees was into the equal percent?
lik lets say 54 was 10% of 360. then the distance traveled owuld be 1 inch(im not saying thats the answer im just trying to explain what i said

 

[WEEGEE SEE ALL]

1. is 1/2 sin 2x the same expression as sin x? justify your answer (i dont even know where to start)

Do you remember the identity for sin 2x? sin 2x = 2 sin x cos x.

So is (1/2) sin 2x the same as sin x?

BTW, use parentheses around fractions.

remember? i was dead serious when i said i was never taught. he threw the regents test at me and gave me 3 problems from it.
so out of what i understand sin x would be equal to sin x cos x right? i understand that there not equal but not really how you got it

 

[WEEGEE SEE ALL]

If you can't answer yes or no to #1, I suggest you select a value for x, say 20°. Then find the sin of 20°. Then find the sin of 40° and take half of it. Then compare results. At least you will be able to say yes or no.

how do you find the sin of....ANYTHING. i understand what you mean to do just give x a representation, but i have no knowledge of any of this. everything i wrote was all i was given. the only difference is number 2 had a diagram

 

[WEEGEE SEE ALL]

[quote="WEEGEE SEE ALL":n1w7gm7c]

im not expecting an answer from anyone just an explanation of what i have to do. in the end i need to explain how i solved this so the explanation is somewhat more important than the answer. im in a catch the fish or teach the man to fish situation

The best way to learn to catch "mathematical" fish - is to open the book and do the example problems of the chapter. Then come to us with work and indicating exactly where you are stuck. If you don't tell us that - we may have to assume you don't know where the river bank is - and your catching fish will be delayed.

In other words - if you really want to learn - show us some work.[/quote:n1w7gm7c]
your not understanding i was left to the dogs basically. no book just 3 problems off a test.tellin me to show you work is like telling me to catch fish in the middle of the desert. i have nothing.i just did "too good" apparently and this was what i got. if you know a place online that can show me closely related examples then i'll take thjat

 

[DrMike]

If you were not taught anything, you need to find a way to teach yourself. You'll need some reference material - something containing an explanation of the stuff you need to teach yourself. As a possibility, you might start here : http://en.wikipedia.org/wiki/Trigonometric_functions - I'm not saying that this is the best or even a good place to start. But it is a possible place to start.

 

[WEEGEE SEE ALL]

If you were not taught anything, you need to find a way to teach yourself. You'll need some reference material - something containing an explanation of the stuff you need to teach yourself. As a possibility, you might start here : http://en.wikipedia.org/wiki/Trigonometric_functions - I'm not saying that this is the best or even a good place to start. But it is a possible place to start.

thanks ill try it

 

[Deleted member 4993]

2. a ball is rolling in a circular path that has a radius of 10 inches. what distance has the ball rolled when the subtended arc is 54 degrees.

Do you know how many degrees there are in one complete revolution? 360°

54° is what fraction of that?

Find the circumference of the ball, which would be the distance rolled in one revolution, then multiply by that fraction.

so what i think what your saying is find out what percent 54 is of 360 right?
i dont think i know how to solve the circumference. C(ircumference) = ? * D(iameter)

If this teacher is trying to give encouragement for your doing well in "math a" - by giving these problems (without any guidance or books) - then don't just walk away - run away from this teacher.

would getting the diameter calling that 100% and then converting what the 54 degrees was into the equal percent?
lik lets say 54 was 10% of 360. egad = no - let's not say that - let's calculate

\(\displaystyle \frac{54}{360} \, = \, 0.15 \, = \, 15 \, percent\)

then the distance traveled owuld be 1 inch(im not saying thats the answer im just trying to explain what i said

Incorrect

Circumference travels 360° - here you are travelling 15% of that

circumference travels (? * d = 22/7 * 20 = 440/7 = ~) 63 inch - you'll travel 15% of that = 63 * 0.15 = 9.45 inch

 

[Denis]

i dont think i know how to solve the circumference....

Are you serious? What the heck WAS math a then? :shock: