MathDB
ab-cd

Source:

March 23, 2008
trigonometrycomplex numbers

Problem Statement

Suppose that a,b,c,d a, b, c, d are real numbers satisfying abcd0 a \geq b \geq c \geq d \geq 0, a^2 \plus{} d^2 \equal{} 1, b^2 \plus{} c^2 \equal{} 1, and ac \plus{} bd \equal{} 1/3. Find the value of ab \minus{} cd.