1)SAT两角和公式 sin(A+B)=sinAcosB+cosAsinB sin(A-B)=sinAcosB-sinBcosA cos(A+B)=cosAcosB-sinAsinB cos(A-B)=cosAcosB+sinAsinB tan(A+B)=(tanA+tanB)/(1-tanAtanB) tan(A-B)=(tanA-tanB)/(1+tanAtanB) cot(A+B)=(cotAcotB-1)/(cotB+cotA) cot(A-B)=(cotAcotB+1)/(cotB-cotA) 2)SAT倍角公式 tan2A=2tanA/[1-(tan^2)A] cot2A=[(cot^2)A-1]/2cotA cos2A=cos^2A-sin^2=2(cos^2)A-1=1-2(sin^2)A sin2A=2sinAcosA 3)SAT半角公式 sin(A/2)=√((1-cosA)/2) sin(A/2)=-√((1-cosA)/2) cos(A/2)=√((1+cosA)/2) cos(A/2)=-√((1+cosA)/2) tan(A/2)=(+&-)√((1-cosA)/((1+cosA))=√(sinA/(1+cosA)) =√((1-cosA)/sinA) cot(A/2)=(+&-)√((1+cosA)/((1-cosA)) 4)SAT和差化积 2sinAcosB=sin(A+B)+sin(A-B) 2cosAsinB=sin(A+B)-sin(A-B) 2cosAcosB=cos(A+B)-sin(A-B) -2sinAsinB=cos(A+B)-cos(A-B) sinA+sinB=2sin((A+B)/2)cos((A-B)/2) cosA+cosB=2cos((A+B)/2)cos((A-B)/2) tanA+tanB=sin(A+B)/cosAcosB tanA-tanB=sin(A-B)/cosAcosB cotA+cotBsin(A+B)/sinAsinB -cotA+cotBsin(A+B)/sinAsinB |