Question

在三角形ABC中，A=45°，cosC=五分之四，b=根号二，求边a,c？

需要文字解说等详细过程，谢谢大佬们

Answer 1

cosC=4/5
sinC=√（1-cos²C）=3/5
sinA=cosA=√2/2
sinB=sin(A+C)=sinAcosC+cosAsinC=7√2/10
a/sinA=b/sinB=c/sinC
a=b*sinA/sinB=√2*(√2/2)/(7√2/10)=5√2/7
c=b*sinC/sinB=√2*(3/5)/(7√2/10)=5√2/7=6/7