If 2 sin 2 ⁡β – cos 2 ⁡β = 2, then β is
(a) 0ᵒ (b) 90ᵒ (c) 45ᵒ (d) 30ᵒ

CBSE Class 10 Sample Paper for 2022 Boards - Maths Standard [MCQ]
CBSE Class 10 Sample Paper for 2022 Boards - Maths Standard [MCQ]
Last updated at Dec. 16, 2024 by Teachoo
Question 7 If 2 sin^2𝛽 – cos^2𝛽 = 2, then β is (a) 0ᵒ (b) 90ᵒ (c) 45ᵒ (d) 30ᵒ Given 2 sin^2𝛽 – cos^2𝛽 = 2 – cos^2𝛽 = 2 − 2 sin^2𝛽 – 〖𝒄𝒐𝒔〗^𝟐𝜷 = 2(1 − 〖𝒔𝒊𝒏〗^𝟐𝜷) – cos^2𝛽 = 2 cos^2𝛽 0 = 2 cos^2𝛽 "+ " cos^2𝛽 0 = 3 cos^2𝛽 3 cos^2𝛽 = 0 cos^2𝛽 = 0 𝒄𝒐𝒔𝜷 = 0 This is possible if 𝛽 = 90° So, the correct answer is (b)