Question

△abc的内角a,b,c的对边分别为a,b,c.已知bsin(a+c)=2asinc,且a=b

△ABC的内角A,B,C的对边分别为a,b,c.已知asinA+csinC-√2sinc=bsinB
①求B
②若A=75°,b=2,求a,c.

Answer 1

①是√2sinCsinA吧?
由a/sinA=b/sinB=c/sinC得a²＋c²－√2ac=b²
sinB=(a²＋c²－b²)/2ac=√2/2
B=45°
②a/sinA=b/sinB 得a=2(√3－1)
C=60°,b/sinB=c/sinC 得c=√6