c o t 2 15 ∘ − 1 c o t 2 15 ∘ + 1 = Options: A . &nbsp 1 2 B . &nbsp √ 3 2 C . &nbsp 3 √ 3 4 D . &nbsp √ 3

Answer: Option B : B c o t 2 15 ∘ − 1 c o t 2 15 ∘ + 1 = c o s 2 15 ∘ s i n 2 15 ∘ − 1 c o s 2 15 ∘ s i n 2 15 ∘ + 1 = c o s 2 15 ∘ − s i n 2 15 ∘ c o s 2 15 ∘ + s i n 2 15 ∘ = c o s ( 30 ∘ ) = √ 3 2

cot215∘−1cot215∘+1 =

Discussion Forum : Trigonometric Functions

Question -

$\frac{c o t^{2} 15^{\circ} - 1}{c o t^{2} 15^{\circ} + 1}$ =

Options:

A .

\frac{1}{2}

B .

\frac{\sqrt{3}}{2}

C .

\frac{3 \sqrt{3}}{4}

D .

\sqrt{3}

Answer: Option B
:
B

$\frac{c o t^{2} 15^{\circ} - 1}{c o t^{2} 15^{\circ} + 1}$ = $\frac{\frac{c o s^{2} 15^{\circ}}{s i n^{2} 15^{\circ}} - 1}{\frac{c o s^{2} 15^{\circ}}{s i n^{2} 15^{\circ}} + 1}$

= $\frac{c o s^{2} 15^{\circ} - s i n^{2} 15^{\circ}}{c o s^{2} 15^{\circ} + s i n^{2} 15^{\circ}}$ = $c o s (30^{\circ})$ = $\frac{\sqrt{3}}{2}$

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Discussion Forum : Trigonometric Functions

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