rbmix.com
evaluate cos20° * cos40° * cos80°  without using calculator
* *


*******
1

1

 cos20° * cos40° * cos80°  without using calculator
----------------------------------------------

-----------------------------------------------
we are going to use sin2x =2sinx cosx
so introduce a 2sin20°
and use the above formula again and again
by introducing 2 whenever necessary
finally ending with sin 160°which is the same as
sin20° using sin(180°-20°) formula
 answer and  some steps are given below
================
* *
================

trig. formulae



**


(index of articles)
formulae on sequences and series
(trig. formulae) 
(integration formulae)
(other math problems without classification) or  problem index
(formulae on differentiation)
rbmix.com
tags: trigonometry, math, homework help, tutor

search
(index of math formulae)
-------------------------------------------------------------------------------------------------------
(homepage)---------------(mixture)----------------(math)-------------(links)-----------(feedback)
----------------------------------------------------------------------------------------


There is no guarantee about the data/information on this site. You use the data/information at your own risk You use the advertisment links presented on this site at your own risk and discretion. We are not responsible for the content of external internet sites. Some of the links may not be correct or may not work.