Question 823998
Given that cos&#945;=(3/4) and 0<&#945;<(&#960;/2), determine the exact value of cos(&#945;/2).
Identity: {{{cos(a/2)=sqrt(((1+cos(a))/2))=sqrt((1+3/4)/2)=sqrt(7/8)}}}
calculator check:
cos(a)=3/4
a&#8776;41.4096&#730;
a/2&#8776;20.7048&#730;
cos(a/2)=cos(20.7048)&#8776;0.9354..
Exact value as calculated=&#8730;(7/8)&#8776;0.9354..