三角函数中的公式和差化积rin = 2 sinASJcoscosA+cosA = 2cos 笼A-BI-cos4-cosB = -2sin-sinA-BTtanX 土 tanB =sin (A B)cosAcosff积化和差2cinasin p = -cos(a *#)*cos(值一户) 2casaccs = cos(ai)4 cos(a-) 2sinaccs =sin(a + 0) + sin(a- P) 2cosa sing = sin(tr+ Q)- sin(a -冷倍角公式二倍角sin2a = 2sinacostf余弦cos 2a cas2 a - sin2=2cos2- 1 -1 -2sin2 it正切2tanataii2(r =1 - W a三倍角sin 3a 二 3sin a - 4sin)r tan3 a - Stana 3= 3tMi2*半角公式a 1 cos LT sin j = JJ -2-a/1 + cos arcos 22sin a1 +cosasin a+ cosa1 co Sit万能公式sin a =-1 +tan2 21 -tan3 ycos a =市1 +tan3 22tan tan a 寸i-w