三角形ABC中a^2+b^2=2c^2求(sin^2A+sin^2B)/Sin^2C0 - 解决时间:2008-5-2 17:12

问题描述:

三角形ABC中a^2+b^2=2c^2求(sin^2A+sin^2B)/Sin^2C
0 - 解决时间:2008-5-2 17:12

a/c=sinA/sinC,b/c=sinA/sinC
a^2/c^2=sin^2A/Sin^2C,b^2/c^2=sin^2B/Sin^2C .
(sin^2A+sin^2B)/Sin^2C =(a^2+b^2)/c^2=2