鋭角三角形ABCについて次の不等式を示せ

2(sinA+sinB+sinC)＞3(cosA+cosB+cosC)

sinA+sinB+sinC＞2+min{A/4,B/4,C/4}


http://www.casphy.com/bbs/test/read.cgi/highmath/1102511185/l50
より