Answer:
[tex]\frac{1-\sqrt{3} }{4}[/tex]
Step-by-step explanation:
By using the sum and difference identities of cos 225 and cos 75 you can find their exact values are [tex]-\frac{\sqrt{2} }{2}[/tex] and [tex]\frac{\sqrt{6}-\sqrt{2} }{4}[/tex] respectively. Then, all you have to do is multiply the fractions together to get [tex]\frac{1-\sqrt{3} }{4}[/tex].
