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？ )。