I need help with some math

Welcome to Hypography, a forum for science and technology. Registration is fast, simple and absolutely free so please, join our community today! If you have any problems with the registration process or your account login, please contact us.

		Science Forums > Help and Advice > Questions and Answers
I need help with some math

LinkBack

Question Tools

Published by ThisIsMyName 11-19-2007

I'm doing a Pre-Calculus section review & this section has been difficult for me. So I do have quite a few questions.

No, they're not "Give me the answer" questions... They're "Am I doing this right?" questions.

The first one I have is about Graphs of Trigonometric Functions: Angles/Radians.
The instructions are: Evaluate each expression.

Sin 7π/6.

OK, the problem with this one is I'm not sure which formula I should use to solve it.

2. Instructions (same section): Given the measurement of a central angle, find the length of its interception arc in a circle of radius 14 centimeters. Round to the nearest tenth.

5π/12

What I want to do:
5π/12 x π/180

and then s=rө
s= 14(ans)

I don't have my calculator on me at the moment.... All I want to know is if that's the right track... not the answer*

3. Find the area of each sector given its central angle ө and the radius of the circle. Round to the nearest tenth.

ө= 5π/12, r= 10

A= 1/2r^2ө

Is that the formula I need?

4. Find each value by referring to the graph of the sine or the cosine function.

sin 11π

I have no idea. I need a formula for this one, too.

Think anyone can help me out??

(Again, I don't want answers...... just formulas and/or "Yeah! You're on the right track!" or "You need to rethink your process."

Thanks!

By billby on 11-19-2007

Re: I need help with some math

Quote:

Originally Posted by ThisIsMyName

The first one I have is about Graphs of Trigonometric Functions: Angles/Radians.
The instructions are: Evaluate each expression.

Sin 7π/6.

OK, the problem with this one is I'm not sure which formula I should use to solve it.

ok so by the looks of things you want a numerical value for $sin(7\pi)$
this is a nice simple question that i think is supposed to get you to think about the nature of periodic functions, like the sine function.
so my advice would be, forget formule and just remember that functions like sine and cosine are periodic, ie. $sin 0 = sin (2\pi)$

as i can't quite tell for sure what question 2 is asking, i have my suspicions but they can pipe down, so i won't offer any assistance there.

Quote:

Originally Posted by ThisIsMyName

3. Find the area of each sector given its central angle ө and the radius of the circle. Round to the nearest tenth.

ө= 5π/12, r= 10

A= 1/2r^2ө

Is that the formula I need?

you can use that formula.

Quote:

Originally Posted by ThisIsMyName

4. Find each value by referring to the graph of the sine or the cosine function.

sin 11π

I have no idea. I need a formula for this one, too.

you seem to be a bit reliant on formule, again this boils down to sine being a periodic function. so there would be two ways of doing this, simplify $sin(11\pi)$ as you did (or maybe will do) in question 1 or draw your graph of $sin x$

well i hope i was of some help and didn't give away too much.

By ThisIsMyName on 11-19-2007

Re: I need help with some math

Thank you, you were... But aren't formulas what math is all about?

By billby on 11-20-2007

Re: I need help with some math

to a degree yes. knowing a formula is all well and good but if you can understand how the formula comes about and gives the result it does you won't be sitting in a maths exam wondering which formula to use.

By ThisIsMyName on 11-20-2007

Re: I need help with some math

T.T It's a miracle I got past fourt grade multiplication, nonetheless Calculus. *cries*

I appriciate your help (again) THANKS! ^.^

By sanctus on 11-25-2007

Re: I need help with some math

For the formula used in question 3 there is an easy "mnemotechnic" (and also shows the utility of radians). The area of a section is always ${\it A}=\frac{1}{2}\theta r^2$ even if the section is the full circle, then you just get the usual formula for the area of a circle; replacing $\theta$ with $2\pi$ you get just:
${\it A}_{circle}=\pi r^2$

Bookmarks

Currently Active Users Viewing This Question: 1 (0 members and 1 guests)

Question Tools
Show Printable Version Email this Page

Posting Rules
You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Trackbacks are On Pingbacks are On Refbacks are On

Similar Threads
Question	Question Starter	Category	Comments	Last Post
Mental math	Rosy	Websites	0	11-14-2007 03:02 AM
Math Help Needed!	sherman	Physics and Mathematics	15	01-25-2006 06:05 AM
New Math Identity?	cindy 2005	Physics and Mathematics	19	08-29-2005 03:42 AM
Math problem	User2983	Physics and Mathematics	6	04-28-2005 05:52 AM

All times are GMT -8. The time now is 08:34 PM.

I need help with some math

Hypography?

Share the love!

Sponsors

Friends