# How much is alpha?

• Jun 19th 2011, 02:54 AM
yehoram
How much is alpha?
Hello !

We have a square - find alpha ?
• Jun 19th 2011, 03:04 AM
Plato
Re: How much is alpha?
There is not enough information to answer.
There must be more given. What else do you know?
• Jun 19th 2011, 03:16 AM
yehoram
Re: How much is alpha?
Quote:

Originally Posted by Plato
There is not enough information to answer.
There must be more given. What else do you know?

Sorry !

This is a square !
• Jun 19th 2011, 03:59 AM
Re: How much is alpha?
Rotate triangle AEB about B, until A rests on C.
Label the new position of "E" as "G".
Draw a line from E to G.
Angle EBG is 90 degrees.
Angles BEG and BGE are 45 degrees.
Use Pythagoras' Theorem to calculate |EG|

Triangle ECG now has all 3 sides (if you let |AE|=1, |EB|=2, |EC|=3)
and you rearrange the law of cosines to calculate "alpha-45" degrees
and therefore "alpha".
• Jun 19th 2011, 04:08 AM
yehoram
Re: How much is alpha?
Quote:

Rotate triangle AEB about B, until A rests on C.
Label the new position of "E" as "G".
Draw a line from E to G.
Angle EBG is 90 degrees.
Angles BEG and BGE are 45 degrees.
Use Pythagoras' Theorem to calculate |EG|

Triangle ECG now has all 3 sides (if you let |AE|=1, |EB|=2, |EC|=3)
and you rearrange the law of cosines to calculate "alpha-45" degrees
and therefore "alpha".

Thank you !

You're a genius ! God blesse you !