MCQ
Choose the correct answer. The value of $\tan75^\circ-\cot75^\circ$ is equal to:
  • $2\sqrt{3}$
  • B
    $2+\sqrt{3}$
  • C
    $2-\sqrt{3}$
  • D
    $1$

Answer

Correct option: A.
$2\sqrt{3}$
$\tan75^\circ-\cot75^\circ=\frac{\sin75^\circ}{\cos75^\circ}-\frac{\cos75^\circ}{\sin75^\circ}\\=\frac{2(\sin^275^\circ-\cos^275^\circ)}{2\sin75^\circ\cos75^\circ}$
$=\frac{-2\cos150^\circ}{\sin150^\circ}$
$=-2\cot150^\circ$
$=-2\cot(180^\circ-30^\circ)$
$=2\cot30^\circ$
$=2\sqrt3$

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