a=√5,b=3sinC=2sinAa/sinA=c/sinCc=asinC/snA=2√5cosA=(b^2+c^2-a^2)/2bc=2/√5sinA=1/√5sin2A=4/5cos2A=1-2(sinA)^2=3/5sin(2A-π/3)=(4/5)*1/2-(3/5)√3/2=(4-3√3)/10
