(a) Using the exact values of the tangents of 3/4 and 7/3, and the angle difference identity for tangent, show that an exact value of tan(57/12) is 2+\sqrt{3} (b) Use the double-angle identity for tangent, and the exact value oftan(57/6), for a different way to find an exact value of tan(5/12). (c) Use an appropriate trigonometric identity involving tan² to show that an exact value of cos(5/12) is \frac{1}{2 \sqrt{2+\sqrt{3}}}

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