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Sin A = 2 Sin (A/2) cos (A/2) Cos A = cos² (A/2) - Sin² (A/2) tan A = 2 tan (A/2)/[1-tan² (A/2)] Cos A = 1 - 2Sin² (A/2) Cos A = 2Cos² (A/2) - 1 sin A = 2 tan (A/2)/[1+tan² (A/2)] cos A = [1-tan²(A/2)]/[1+tan² (A/2)] sin²A/2 = (1-Cos A)/2 Cos²A/2 = (1+Cos A)/2 tan²(A/2) = (1-Cos A)/(1+Cos A) |
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