Hello,Two smallapproximation formulas of pi.  Formula 5:A formula that weighs,the number of terms explodes with m. Pi=Limit(1/2^(m-1)*(1+2*Sum(sqrt(1-((n^2)*2^(-2*m))),n=1..2^(m)-1)),m=infinity); Formula 6:if Lambda istaken in the interval ] 1; 1 [ and different from 0, -1 / 2,1 / 2, -1 / 4,1 / 4. Pi=(1/lambda)*Sum(((-1)^(n+1)/(2*n-1))*((tan(lambda*Pi))^(2*n-1))*cos((4*n-2)*lambda*Pi),n=1..infinity)+(1/lambda)*Sum(((-1)^(n+1)/(2*n))*((tan(lambda*Pi))^(2*n))*sin((4*n)*lambda*Pi),n=1..infinity);