do me a favorBC中,角A,B,C所对的边分别为a,b,c,若sinA^2+sinC^2-sinB^2=根号3sinAsinC,则角B为

来源：学生作业帮助网 编辑：作业帮 时间：2024/11/18 11:38:11
do me a favorBC中,角A,B,C所对的边分别为a,b,c,若sinA^2+sinC^2-sinB^2=根号3sinAsinC,则角B为
xRKNAJ%&fMZFfnHzZM\, ш 20|\ ,

do me a favorBC中,角A,B,C所对的边分别为a,b,c,若sinA^2+sinC^2-sinB^2=根号3sinAsinC,则角B为
do me a favor
BC中,角A,B,C所对的边分别为a,b,c,若sinA^2+sinC^2-sinB^2=根号3sinAsinC,则角B为

do me a favorBC中,角A,B,C所对的边分别为a,b,c,若sinA^2+sinC^2-sinB^2=根号3sinAsinC,则角B为
由正弦定理:
a/sinA = b/sinB = c/sinC = 2R
可知
sinA = a/2R,sinB = b/2R,sinC = c/2R 代入原等式
(a/2R)² + (c/2R)² - (b/2R)² = √3 (a/2R)(c/2R) 化简得到
a² + c² - b² = √3ac -①
余弦定理:cosB = (a² + c ² -b²) / (2ac) ②
将①代入② 得到
cosB = √3ac/(2ac) = √3/2
所以∠B = 30°

do me a favorBC中,角A,B,C所对的边分别为a,b,c,若sinA^2+sinC^2-sinB^2=根号3sinAsinC,则角B为 do me a favor do me a will you do me a favor?中do是成分,为什么放在me后. Please do me a favor do me a favour do是什么意思 英语翻译Would you do me a favor? can you do me a favour? Can you do a favour for me? Can you do me a favour Can you do me a favour do you love me a littl Do you love me a littl 怎样翻译do me a favor? would you do me a favor?意思? Do you have a crush on me? do me a favor　　的意思 do me a favor的翻译?