在三角形ABC中,(sinA-sinB)/sin(A+B)=(√2sinA-sinC)/(sinA+sinB)
问题描述:
在三角形ABC中,(sinA-sinB)/sin(A+B)=(√2sinA-sinC)/(sinA+sinB)
(1)求B
(2) 若cosA=3/5,求sinC的值
答
(1)(sinA-sinB)/sin(A+B)=(√2sinA-sinC)/(sinA+sinB)∴(sinA-sinB)(sinA+sinB)=sin(A+B)(√2sinA-sinC)sin²A-sin²B=sin(A+B)[√2sinA-sin(A+B)]sin²A-sin²B=√2sinAsin(A+B)-sin²(A+B)sin...