Question 25
Find the largest value of the expression
$$
x y + x \sqrt{1 - y^{2}} + y \sqrt{1 - x^{2}} - \sqrt{(1 - x^{2})(1 - y^{2})}
$$
$$
x y + x \sqrt{1 - y^{2}} + y \sqrt{1 - x^{2}} - \sqrt{(1 - x^{2})(1 - y^{2})}
$$
MathNet 1994 — Part 01 Question 25
Math Olympiad Vault · MathNet 1994 — Part 01