Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 202125 JulyEvening Shift
Exam
JEE Main
Year
2021
Date
25 July
Shift
Evening Shift
Subject
Mathematics
Chapter
Trigonometric Ratios & Identities

JEE Main 2021 · 25 July · Evening Shift · Mathematics · Trigonometric Ratios & Identities

The value of cot(π)/(24) is:

The value of cotπ24cot\dfrac{\pi}{24} is:

Options

  1. A2+3+2−6\sqrt{2} + \sqrt{3} + 2 - \sqrt{6}
  2. B2+3+2+6\sqrt{2} + \sqrt{3} + 2 + \sqrt{6}
  3. C2−3−2+6\sqrt{2} - \sqrt{3} - 2 + \sqrt{6}
  4. D32−3−63\sqrt{2} - \sqrt{3} - \sqrt{6}

Correct answer

B. 2+3+2+6\sqrt{2} + \sqrt{3} + 2 + \sqrt{6}

Step-by-step solution

We know that cotθ=1+cos⁡2θsin⁡2θcot\theta = \dfrac{1 + \cos 2\theta}{\sin 2\theta}

Since, θ=π24\theta = \dfrac{\pi}{24}

Therefore, cotθ=1+(3+122)(3−122)cot\theta = \dfrac{1 + \left(\dfrac{\sqrt{3} + 1}{2\sqrt{2}}\right)}{\left(\dfrac{\sqrt{3} - 1}{2\sqrt{2}}\right)}

⇒cot⁡(π24)=1+(3+122)(3−122)⇒ \cot \left(\dfrac{\pi}{24}\right) = \dfrac{1 + \left(\dfrac{\sqrt{3} + 1}{2\sqrt{2}}\right)}{\left(\dfrac{\sqrt{3} - 1}{2\sqrt{2}}\right)}

=(22+3+1)(3−1)×(3+1)(3+1)= \dfrac{\left(2\sqrt{2} + \sqrt{3} + 1\right)}{\left(\sqrt{3} - 1\right)} \times \dfrac{\left(\sqrt{3} + 1\right)}{\left(\sqrt{3} + 1\right)}

=26+22+3+3+3+12= \dfrac{2\sqrt{6} + 2\sqrt{2} + 3 + \sqrt{3} + \sqrt{3} + 1}{2}

=6+2+3+2.= \sqrt{6} + \sqrt{2} + \sqrt{3} + 2 .

Practice Trigonometric Ratios & Identities on Quantrex Academy →

More from Trigonometric Ratios & Identities

Let α = (1 - 2 ((π)/(11)))(1 - 2 ((3π)/(11)))(1 - 2 ((9π)/(11)))(1 - 2 ((27π)/(11)))(1… JEE Advanced 2026If A = ( 3^∘)/( 9^∘) + ( 9^∘)/( 27^∘) + ( 27^∘)/( 81^∘) and B = 81^∘ - 3^∘ , then (B)/(A)… JEE Main 2026Let P = \ θ ∈ [0, 4π] : ^2θ ≠ 1\ and S = \ a ∈ ℤ : 2( ^8θ - ^8θ) 2θ = a^2, θ ∈ P\ . Then… JEE Main 2026If ((π)/(18)) ((5π)/(18)) ((7π)/(18)) = K , then the value of ((10Kπ)/(3)) is : JEE Main 2026If (A-B) A + ^ 2 C ^ 2 ~A =1, ~A, ~B, C ∈(0, (π)/(2)) , then JEE Main 2026If x=(5)/(12) for some x ∈(π, (3 π)/(2)) , then 7 x( (13 x)/(2)+ (13 x)/(2))+ 7 x( (13… JEE Main 2026The value of 3 cosec 20^ ∘ - 20^ ∘ 20^ ∘ 40^ ∘ 60^ ∘ 80^ ∘ is equal to JEE Main 2026The least value of ( ^ 2 θ-6 θ θ+3 ^ 2 θ+2) is JEE Main 2026Let (π)/(2) ((15 θ)/(2))( 8 θ+ 8 θ)+ ((15 θ)/(2))( 8 θ- 8 θ) is equal to JEE Main 2026Let α and β respectively be the maximum and the minimum values of the function f(θ)=4( ^… JEE Main 2026Let (α+β)=-(1)/(10) and (α-β)=(3)/(8) , where 0<α<(π)/(3) and 0<β<(π)/(4) . If 2 α= 3(1-r… JEE Main 2026If ^ 2 48^ ∘ - ^ 2 12^ ∘ ^ 2 24^ ∘ - ^ 2 6^ ∘ = α+β 5 2 , where α, β ∈ ℕ , then α+β is… JEE Main 2026The value of cosec 10^ ∘ - 3 10^ ∘ is equal to : JEE Main 2026Let α= 1 60^ ∘ 61^ ∘ + 1 62^ ∘ 63^ ∘ +…+ 1 118^ ∘ 119^ ∘ Then the value of ( cosec 1^ ∘ α… JEE Advanced 2025If x+ ^2 x=1, x ∈(0, (π)/(2)) , then ( ^ 12 x+ ^ 12 x)+3( ^ 10 x+ ^ 10 x+ ^8 x+ ^8 x)+(… JEE Main 2025If ∑_ r=1 ^ 13 \ (1)/( ((π)/(4)+(r-1) (π)/(6)) ((π)/(4)+(r π)/(6)))\ =a 3 +b, a, b ∈ Z… JEE Main 2025 Full Trigonometric Ratios & Identities list Trigonometric Ratios & Identities JEE Maths PYQsJEE Mathematics PYQs All JEE Main PYQs