My Math Forum  

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

Algebra Pre-Algebra and Basic Algebra Math Forum


Reply
 
LinkBack Thread Tools Display Modes
March 19th, 2013, 05:36 AM   #1
Senior Member
 
Joined: Sep 2012

Posts: 199
Thanks: 1

Area problem

I am having problem with this question, I am not 100% that I have worked it out the right way.

Question: An enclosure PQRS is to be made as shown, in the figure ( my diagram ). PQ and RQ are fences of total length of 300m. The other two sides are hedges. The angles at Q and R are right angles and the angle at S is 135 degree. The length of QR is x meters.

a) show that the area, A m^2, of the enclosure is given by:

I will show my working in steps:
1.

So after this I have to find the area so what is did was

2. take my red triangle I have the opposite of length x and a angle of I then used this to workout the hypotenuse.

3.hypotenuse


4. I then workout the adjacent

So the area of the red triangle

5. I then workout the area of the rectangle

what did then was take the area of the rectangle and minus the area of the triangle

6.

This gives the right ans, but I don't think what I have done correct, or if I have is there a quicker way, I did spot that I could have used area of trapezium but was not really sure how to apply that.

Could someone please point out anywhere I have gone wrong or even show another way around this question.
Attached Images
File Type: png Area problem.png (11.0 KB, 245 views)
taylor_1989_2012 is offline  
 
March 19th, 2013, 06:52 AM   #2
Senior Member
 
Joined: Sep 2012

Posts: 199
Thanks: 1

Re: Area problem

Right I have over complicated things slight, just realised that because it's a 45 degree triangle adjacent and opposite will be the same length.
taylor_1989_2012 is offline  
March 19th, 2013, 09:24 AM   #3
Math Team
 
Joined: Oct 2011
From: Ottawa Ontario, Canada

Posts: 10,663
Thanks: 697

Re: Area problem

Can't see your diagram (except top part)
Denis is offline  
March 19th, 2013, 10:20 AM   #4
Senior Member
 
Joined: Sep 2012

Posts: 199
Thanks: 1

Re: Area problem

Strange I will try repost the diagram. I have notice I have smiles in my first post which I did not put in there. Has my post been edit?
taylor_1989_2012 is offline  
March 19th, 2013, 10:47 AM   #5
Senior Member
 
Joined: Sep 2012

Posts: 199
Thanks: 1

Re: Area problem

It seem to be okay to me, I just double clicked on the diagram. Have another go other wise, I will take a photo on the diagram out of my book a post it up. Problem is not to sure how good the quality will be.
taylor_1989_2012 is offline  
March 19th, 2013, 10:54 AM   #6
Senior Member
 
Joined: Sep 2012

Posts: 199
Thanks: 1

Re: Area problem

Here is photo out of book. Not great but best I could do.
Attached Images
File Type: jpg photo.JPG (253.8 KB, 207 views)
taylor_1989_2012 is offline  
March 19th, 2013, 11:14 AM   #7
Math Team
 
Joined: Nov 2010
From: Greece, Thessaloniki

Posts: 1,989
Thanks: 133

Math Focus: pre pre pre pre pre pre pre pre pre pre pre pre calculus
Re: Area problem

[attachment=0cyy7l7y]as.png[/attachmentcyy7l7y]

.
Attached Images
File Type: png as.png (13.2 KB, 205 views)
ZardoZ is offline  
March 19th, 2013, 11:59 AM   #8
Senior Member
 
Joined: Sep 2012

Posts: 199
Thanks: 1

Re: Area problem

That's what I got the first time I did the question. But it say I should show the area to be .
taylor_1989_2012 is offline  
March 19th, 2013, 12:15 PM   #9
Math Team
 
Joined: Nov 2010
From: Greece, Thessaloniki

Posts: 1,989
Thanks: 133

Math Focus: pre pre pre pre pre pre pre pre pre pre pre pre calculus
Re: Area problem

[color=#000000]
Quote:
Originally Posted by taylor_1989_2012
That's what I got the first time I did the question. But it say I should show the area to be .
Oh sorry, I gave wrong names to the vertices. My figure is wrong. In that case .[/color]
ZardoZ is offline  
March 19th, 2013, 12:54 PM   #10
Senior Member
 
Joined: Sep 2012

Posts: 199
Thanks: 1

Re: Area problem

Okay no worries. Could you expand on you method a bit more. I see you have add the areas, where I worked out the whole area of the rectangle and then misused the area for the triangle. Yet will still have the same ans. I think the bit that is confusing is where did you get the (300-2x) from?

Thank by the way for the help.
taylor_1989_2012 is offline  
Reply

  My Math Forum > High School Math Forum > Algebra

Tags
area, problem



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
Inverse Tan area problem mr. jenkins Calculus 7 March 10th, 2014 08:02 PM
Area problem Imaxium Algebra 8 May 22nd, 2013 04:12 AM
Triangle area problem... tahir.iman Algebra 9 December 19th, 2012 04:35 AM
Area Problem omarg Calculus 2 November 26th, 2012 05:20 PM
Area Problem julian21 Algebra 1 October 15th, 2010 11:16 PM





Copyright © 2017 My Math Forum. All rights reserved.