Math Is Fun Forum

tony123

Member

Registered: 2007-08-03

Posts: 229

prove that

prove that

Last edited by tony123 (2008-04-22 09:44:58)

John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: prove that

In degrees, it is easier for me because I like to add 2 numbers to be 90.
Complimentary angles are used a lot here.
s7.5s37.5s52.5s82.5=1/16
(s7.5c7.5)(s37.5c37.5)=1/16
(1/2sin15)(1/2sin75)=1/16
1/4(s15s75)=1/16
s15s75=1/4
s15c15=1/4
1/2sin30=1/4
(1/2)(1/2)=1/4  Yes!

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