![File:Plot f(x,theta)=product(exp (devide(-pow(x,2),product(2,pow(sigma,2)))),cos(product(2,pi,theta,x))); sigma=1; theta=range(0.1,9.9).gif - Wikimedia Commons File:Plot f(x,theta)=product(exp (devide(-pow(x,2),product(2,pow(sigma,2)))),cos(product(2,pi,theta,x))); sigma=1; theta=range(0.1,9.9).gif - Wikimedia Commons](https://upload.wikimedia.org/wikipedia/commons/4/4e/Plot_f%28x%2Ctheta%29%3Dproduct%28exp%28devide%28-pow%28x%2C2%29%2Cproduct%282%2Cpow%28sigma%2C2%29%29%29%29%2Ccos%28product%282%2Cpi%2Ctheta%2Cx%29%29%29%3B_sigma%3D1%3B_theta%3Drange%280.1%2C9.9%29.gif)
File:Plot f(x,theta)=product(exp (devide(-pow(x,2),product(2,pow(sigma,2)))),cos(product(2,pi,theta,x))); sigma=1; theta=range(0.1,9.9).gif - Wikimedia Commons
In Euler's identity e^ix = cos x +I sin x , we put x=pi then we get e^I pi = -1 , but if x is in degree then e^I pi does
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