Warning: Illegal string offset 'html' in /home/hsn/public_html/forum/cache/skin_cache/cacheid_1/skin_topic.php on line 909

Warning: Cannot modify header information - headers already sent by (output started at /home/hsn/public_html/forum/cache/skin_cache/cacheid_1/skin_topic.php:909) in /home/hsn/public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 114

Warning: Cannot modify header information - headers already sent by (output started at /home/hsn/public_html/forum/cache/skin_cache/cacheid_1/skin_topic.php:909) in /home/hsn/public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 127

Warning: Cannot modify header information - headers already sent by (output started at /home/hsn/public_html/forum/cache/skin_cache/cacheid_1/skin_topic.php:909) in /home/hsn/public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 136

Warning: Cannot modify header information - headers already sent by (output started at /home/hsn/public_html/forum/cache/skin_cache/cacheid_1/skin_topic.php:909) in /home/hsn/public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 137

Warning: Cannot modify header information - headers already sent by (output started at /home/hsn/public_html/forum/cache/skin_cache/cacheid_1/skin_topic.php:909) in /home/hsn/public_html/forum/admin/sources/classes/output/formats/html/htmlOutput.php on line 141
How do i go about solving this question? - straight line - HSN forum

Jump to content


How do i go about solving this question? - straight line


3 replies to this topic

#1 umhellothere

    Newbie

  • Members
  • Pip
  • 3 posts
  • Location:Helensburgh
  • Interests:Maths!
  • Gender:Female

Posted 15 September 2008 - 05:38 PM

The right-angled triangle OAB with sides of length 3cm, 4cm and 5cm is placed with one vertex at the origin as shown in the diagram.

A circle centre C and diameter RO of length 13cm is drawn and passes through O and B.

What is the gradient of the line RO?


My scanner isn't working so i've attached a (really bad) sketch of what the diagram looks like, i didn't draw the circle because my paint skills ain't up to that much!





*I have been trying for ages to get this answer but my mind just goes blank everytime i look at it. I don't have any idea of what formula/method to use so just a nudge in the right direction would help me a lot thanks for any help you can give*

Attached Files



#2 Steve

    Top of the Class

  • Admin
  • PipPipPipPipPip
  • 435 posts
  • Location:Edinburgh
  • Gender:Male

Posted 16 September 2008 - 09:03 AM

Welcome to the forum!

I'll give you a little hint: it relies on the fact from Standard Grade/Int2 that a triangle in a semi-circle is right-angled. You can then use trigonometry to work out the angle between OR and the x-axis.

Hope this helps. smile.gif
HSN contribute: Help the site grow!

Looking for a Maths tutor in West Lothian? Just PM me!

#3 umhellothere

    Newbie

  • Members
  • Pip
  • 3 posts
  • Location:Helensburgh
  • Interests:Maths!
  • Gender:Female

Posted 16 September 2008 - 03:51 PM

QUOTE(Steve @ Sep 16 2008, 10:03 AM) View Post
Welcome to the forum!

I'll give you a little hint: it relies on the fact from Standard Grade/Int2 that a triangle in a semi-circle is right-angled. You can then use trigonometry to work out the angle between OR and the x-axis.

Hope this helps. smile.gif


yes it really helped! Does -3.93 sound about right for the answer? , thanks for getting me started smile.gif



#4 Steve

    Top of the Class

  • Admin
  • PipPipPipPipPip
  • 435 posts
  • Location:Edinburgh
  • Gender:Male

Posted 18 September 2008 - 08:19 AM

That's not what I got, but I could be wrong!

Here's my working:

Since the triangle in the semi-circle is right-angled, RB = 12 (using Pythagoras's Theorem). Then using trigonometry, angle ROB = 78.91 degrees and angle BOA = 36.87 degrees.

So OR makes an angle of 78.91 + 36.87 = 115.78 degrees with the x-axis. Then we can use the formula m=\tan\theta to find the gradient. I get -2.07.
HSN contribute: Help the site grow!

Looking for a Maths tutor in West Lothian? Just PM me!





1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users