testing header
Math Goodies is a free math help portal for students, teachers, and parents.
Free Math
Newsletter
 
 
Interactive Math Goodies Software

Buy Math Goodies Software
testing left nav
Math Goodies on facebook

Math Goodies Blog
Math Forums @ Math Goodies
Math Forums @ Math Goodies
Home | Profile | Register | Active Topics | Members | Search | FAQ
 All Forums
 Parent Forum
 Parent's Place
 Solid Geometry - need help please

Note: You must be registered in order to post a reply.
To register, click here. Registration is FREE!

Screensize:
UserName:
Password:
Format Mode:
Format: BoldItalicizedUnderlineStrikethrough Align LeftCenteredAlign Right Horizontal Rule Insert HyperlinkInsert EmailInsert Image Insert CodeInsert QuoteInsert List Insert Special Characters Insert Smilie
   
Message:
* HTML is OFF
* Forum Code is ON

Math Symbols
Squared [squared] Cubed [cubed] Square Root [sqrt] Cube Root [cbrt] Pi [pi]
Alpha [alpha] Beta [beta] Gamma [gamma] Theta [theta] Angle [angle]
Degrees [degrees] Times [times] Divide [divide] Less Than or Equal To [less-than] Greater Than or Equal To [greater-than]
Plus Minus [plus-minus] Integral [integral] Sum [sum] Sub 1 [sub-1] Sub 2 [sub-2]
Element Of [element-of] Union [union] Intersect [intersect] Subset [subset] Empty Set [empty-set]

  Check here to subscribe to this topic.
 
   

T O P I C    R E V I E W
raghu Posted - 04/01/2008 : 13:14:29
there is a cube. Two diagonals from the same vertex are drawn, one as face diagonal and the other as space diagonal. Find the measure of angle between the two diagonals.
This is how I started .
I assumed a 1X1x1 cube. face diagonal came out as sqrt(2) and Space Diagonal came out as sqrt(3). I tried to apply sine rule. There are too many unknowns and hit a brick wall.
Appreciate any help
4   L A T E S T    R E P L I E S    (Newest First)
Subhotosh Khan Posted - 04/01/2008 : 22:36:30
quote:
Originally posted by raghu

Here is how I solved the problem. Face diagonal will be of size sqrt(2) and space diagonal will be sqrt(3).
The angle between the two diagonals will be sine inverse of (1/sqrt3)

correct

. So the angle is 60 degrees.incorrect

sin-1(1/3) = 35.26438968

Mr. Khan,
thanks for the response.

raghu Posted - 04/01/2008 : 18:20:30
Here is how I solved the problem. Face diagonal will be of size sqrt(2) and space diagonal will be sqrt(3).
The angle between the two diagonals will be sine inverse of (1/sqrt3). So the angle is 60 degrees.
Mr. Khan,
thanks for the response.
raghu Posted - 04/01/2008 : 14:45:11
can you please expand on that.
Subhotosh Khan Posted - 04/01/2008 : 14:15:22
Express the diagonals as vectors - then use definition of vector product to find the angle.

Math Forums @ Math Goodies © 2000-2004 Snitz Communications Go To Top Of Page
This page was generated in 0.06 seconds. Snitz Forums 2000
testing footer
About Us | Contact Us | Advertise with Us | Facebook | Blog | Recommend This Page




Copyright © 1998-2015 Mrs. Glosser's Math Goodies. All Rights Reserved.

A Hotchalk/Glam Partner Site - Last Modified 25 Jan 2015