My Math Forum  

Go Back   My Math Forum > High School Math Forum > Trigonometry

Trigonometry Trigonometry Math Forum


Reply
 
LinkBack Thread Tools Display Modes
May 31st, 2015, 10:01 AM   #1
Newbie
 
Joined: May 2015
From: Singapore

Posts: 2
Thanks: 0

Maximum/Minimum value of trigonometry function

Hi,

This is a common CIE A levels P1 paper question, but I seem to have forgotten how to do it:

Find the maximum value and the minimum value of

30/[11-5cos(x/2-45)]

and
8/[3-sin x]

at the least positive value of x at which it occurs.

I understand doing 11-5cos(x/2-45) as being

-1*(-5)+11>11-5cos(x/2-45)>1*(-5)+11
16>11-5cos(x/2-45)>6

and so on... but how do I do this if there is a fraction?

Any help would be appreciated, thank you in advance!
2point718 is offline  
 
May 31st, 2015, 10:19 AM   #2
Global Moderator
 
greg1313's Avatar
 
Joined: Oct 2008
From: London, Ontario, Canada - The Forest City

Posts: 7,437
Thanks: 870

Math Focus: Elementary mathematics and beyond
As both denominators are always positive you don't have to consider negative values. With
the denominator and numerator positive, a fraction with a constant numerator is at a maximum
where the denominator is smallest and at a minimum where the denominator is largest.
greg1313 is online now  
May 31st, 2015, 11:40 AM   #3
Newbie
 
Joined: May 2015
From: Singapore

Posts: 2
Thanks: 0

Hmm... sorry, I still don't understand that. How would you solve the above 2 questions though? Thank you
2point718 is offline  
Reply

  My Math Forum > High School Math Forum > Trigonometry

Tags
function, least positive value, maximum and minimum, maximum or minimum, trigonometry



Search tags for this page
Click on a term to search for related topics.
Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Difference Between Maximum/Minimum Value and Maximum/Minimum Turning Point Monox D. I-Fly Pre-Calculus 4 October 13th, 2014 05:58 AM
Maximum and Minimum Value of a Fraction Function Monox D. I-Fly Pre-Calculus 15 October 9th, 2014 04:50 PM
maximum and minimum of a function Dmath Calculus 4 March 9th, 2014 06:19 PM
Minimum and Maximum of Trig Function ckooiker Calculus 2 November 12th, 2011 09:26 AM
Finding Maximum/minimum of trig function nicolodn Algebra 4 October 10th, 2010 07:39 PM





Copyright © 2017 My Math Forum. All rights reserved.