初中数学各种公式(完整版) (1)

1(ab)(ab)a2b2(ab)2a22abb2(ab)(a2abb2)a3b3(ab)(a2abb2)a3b3a2b2(ab)22ab(ab)2(ab)24ab2amanam+namanam-n(am)namn(ab)nanbn(ab)nnnaba-n1na()-n()na01(a0)3()2a(a0)a(a0b0)4|a|-|b||ab||a|+|b|||a|-|b|||ab||a|+|b|abab|a+b||a|+|b||a-b||a|+|b||a|b=-bab|a-b||a|-|b|-|a|a|a|5n1+2+3+4+5+6+7+8+9++n=n(n+1)/21+3+5+7+9+11+13+15++(2n-1)=n22+4+6+8+10+12+14++(2n)=n(n+1)12+22+32+42+52+62+72+82++n2=n(n+1)(2n+1)/613+23+33+43+53+63+3=n2(n+1)2/41*2+2*3+3*4+4*5+5*6+6*7++n(n+1)=n(n+1)(n+2)/36ax2bxc0x242bbacab24ac000x1x2ax2bxca(xx1)(xx2)abx2(ab)xab07ykxb(k0)(by)k0yx()k0yx()b0ykx(k0)(yx)8y(k0)k0()k0()91.cbacbxaxy,,(2)0ayx2.a0a0aayhx.y0x3.0a0a0xy0,00xy(0,k)(h,0)(h,k)(abacab4422)4.abacabxacbxaxy442222abacab4422abx2khxay2(h,k)hx12(,)(,)xyxyy122xxx5.cbxaxy2cba,,a2axyaba.cbxaxy2abx20by0ababy0ababyccbxaxy2y0xcycbxaxy2y0c0c;0c,y0c,y..y0ab6.cbxaxy2.xy.khxay2.x1x2x21xxxxay7.ycbxaxy2(0,c)xcbxaxy2x1x2x02cbxax.xa(0)xbx(0)xc(0)xx012.2kkcbxax20knkxyl02acbxaxyGcbxaxynkxy2alGblGclGxcbxaxy2x0021xBxA12ABxx101()()2nx1x2xn12......nxxxxn+++==-1x2x,nx2s2s=()()()222121.....nxxxxxxn-+-++-1x2x,nxss=()()()222121.....nxxxxxxn-+-++-111=12PA0AP=1P=012AABCAsinAAcosAAtanAsin2Acos2A10sinA10cosA1tanA0AAsin(90oA)cosAcos(90oA)sinAsin30ocos60osin45ocos45osin60ocos30otan30otan45o1tan60oiitan131a/sinA=b/sinB=c/sinC=2RR(1)a=2RsinA,b=2RsinB,c=2RsinC(2)sinA:sinB:sinC=a:b:c2b2=a2+c2-2accosBa2=b2+c2-2bccosAc2=a2+b2-2abcosCCcBbAa141sin(A+B)=sinAcosB+cosAsinBsin(A-B)=sinAcosB-sinBcosAcos(A+B)=cosAcosB-sinAsinBcos(A-B)=cosAcosB+sinAsinBtan(A+B)=(tanA+tanB)/(1-tanAtanB)tan(A-B)=(tanA-tanB)/(1+tanAtanB)hlctg(A+B)=(ctgActgB-1)/(ctgB+ctgA)ctg(A-B)=(ctgActgB+1)/(ctgB-ctgA)2tan2A=2tanA/(1-tan2A)ctg2A=(ctg2A-1)/2ctgacos2a=cos2a-sin2a=2cos2a-1=1-2sin2a3sin(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))tan(A/2)=-((1-cosA)/((1+cosA))ctg(A/2)=((1+cosA)/((1-cosA))ctg(A/2)=-((1+cosA)/((1-cosA))4sinA+sinB=2sin((A+B)/2)cos((A-B)/2cosA+cosB=2cos((A+B)/2)sin((A-B)/2)tanA+tanB=sin(A+B)/cosAcosBtanA-tanB=sin(A-B)/cosAcosBctgA+ctgBsin(A+B)/sinAsinB-ctgA+ctgBsin(A+B)/sinAsinB52sinAcosB=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)151PabPxP1abPyP2abP3ab2PabhPahbhPahbhPabhhPabh.A2125A7116n(n2)180onn360o171abcl1l2abcABCDEF,,ABDEABDEBCEFBCEFACDFACDF2ABCDEBCDEABACDE,,ADAEADAEDEDBECDBECABACBCABAC18RtABCACB90oCDABD12CDADBD22ACADAB32BCBDAB191234567890o90o92012RtABCabcc2abcrCABDABClSr12Slr211PAC2ACOPAOA1122PACACAOCACOPAOAPACABC221PAPB=PCPD2PAPB=PCPD3PC2=PAPB23S()2SS()1()2SSR2l2RL213602nrSlrS2rhSSS2rh2r2SrbSSSrbr2OPBCA