What is the reciprocal of square root of 2?

It’s ##sqrt(2)/2##.

The reciprocal of ##sqrt(2)## is ##1/sqrt(2)##. We can multiply both the numerator and the denominator by ##sqrt(2)## (we can do that without changing the result, since we’re multiplying by 1) and we get ##1/sqrt(2)*sqrt(2)/sqrt(2)=sqrt(2)/2##. Using decimal digits, it’s a number starting with 0.7071…