solved here:
http://www.goiit.com/posts/list/algebra-if-a-b-c-pi-then-maximum-value-of-cosa-cosb-kcosc-where-912480.htm
find the maximum value of~~ cosA +cosB +kcosC
A+B+C=pi
k<1/2
please help!!
solved here:
http://www.goiit.com/posts/list/algebra-if-a-b-c-pi-then-maximum-value-of-cosa-cosb-kcosc-where-912480.htm