1, the reciprocal formula of exponential formula and logarithmic formula: log? N=b,=N(a>0,a≠ 1,N>0).
2 、( ab)? =a? b? (a>0,b>0,r∈Q).
3. Double angle formula: tan2a = 2tana/[1-(tana) 2]; cos2a=(cosa)^2-(sina)^2=2(cosa)^2 - 1= 1-2(sina)^2; sin2A=2sinA*cosA .
4. General equation of circle: x? +y? +Dx+Ey+F=0(D? +E? -4F>0).
5. The sum of the probabilities of the occurrence of N mutually exclusive events respectively P(A? +A? +A? ...+A? )=P(A? )+P(A? )+...+P(A? )。