text: Both of you equations are not true and cannot be proved.\n\nBy '7/12' I hope you mean 7 upon 12.\n\n7/12 = 0.5833 (recurring)\n1/2  = 0.5\n\nI reconsidered this.\n\n'cos a + sin a' is not always equal to 1.\n\nIt may be applicable to 0°, 45° & 90°\nBut it cannot be considered as a general formula.\n\nsin 30° = 0.5\ncos 30° = 0.866\nsin 30° + cos 30° = 1.36 \n\n     sin 30° + cos 30° ≠ 1\nAlso,\n     sin 60° + cos 60° ≠ 1\nAnother identity is:\n\nsin^2 a + cos^2 a = 1\n( sin a the whole square + cos a the whole square ) = 1