a, b, c are real numbers. such that a^2+b^2+c^2 = 1. prove that 1/2≤(ab+bc+ca)≤1
a^2 + b^2 + c^2 = 1
a, b, and c each have to be <=1 because if either was greater than 1, then a^2 + b^2 + c^2 > 1
a, b, and c each have to be >= -1 because if either was less than -1, then a^2 + b^2 + c^2 > 1
What we have now is: -1 <= a, b, c <= 1
ab, bc, ca each have t Read More: ...