If 2 sin 2 ⁡β – cos 2 ⁡β  = 2, then β is

(a) 0ᵒ   (b) 90ᵒ   (c) 45ᵒ   (d) 30ᵒ

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Question 7 If 2 sin^2⁡𝛽 – cos^2⁡𝛽 = 2, then β is (a) 0ᵒ (b) 90ᵒ (c) 45ᵒ (d) 30ᵒ Given 2 sin^2⁡𝛽 – cos^2⁡𝛽 = 2 – cos^2⁡𝛽 = 2 − 2 sin^2⁡𝛽 – 〖𝒄𝒐𝒔〗^𝟐⁡𝜷 = 2(1 − 〖𝒔𝒊𝒏〗^𝟐⁡𝜷) – cos^2⁡𝛽 = 2 cos^2⁡𝛽 0 = 2 cos^2⁡𝛽 "+ " cos^2⁡𝛽 0 = 3 cos^2⁡𝛽 3 cos^2⁡𝛽 = 0 cos^2⁡𝛽 = 0 𝒄𝒐𝒔⁡𝜷 = 0 This is possible if 𝛽 = 90° So, the correct answer is (b)

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.