6.2 Trigonometric Functions: Unit Circle Approach/43

$2\sec \left({\frac {\pi }{4}}\right)$

Failed to parse (syntax error): {\displaystyle {\frac{\pi}{4})-\cos(45^{\circ}) = \frac{1}{2} - \frac{\sqrt{2}}{2} = \frac{1-\sqrt{2}}{2}}