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Prove that :tan 225° cot 405° + tan 765° cot 675° = 0 |
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Answer» LHS = tan 225° cot 405° + tan 765° cot 675° = tan (90° × 2 + 45°) cot (90° × 4 + 45°) + tan (90° × 8 + 45°) cot (90° × 7 + 45°) We know that when n is odd, cot → tan. = tan 45° cot 45° + tan 45° [-tan 45°] = tan 45° cot 45° - tan 45° tan 45° = 1 × 1 – 1 × 1 = 1 – 1 = 0 = RHS Hence proved. |
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