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Question 7 - CBSE Class 10 Sample Paper for 2022 Boards - Maths Basic [MCQ] - Solutions of Sample Papers for Class 10 Boards

Last updated at Dec. 16, 2024 by Teachoo

If cos⁡θ + cos⁡ 2 θ   = 1, the value of sin 2 ⁡θ + sin 4 ⁡θ is

(a) -1   (b) 0   (c) 1   (d) 2

Transcript

Question 7 If cos⁡𝜃 + cos⁡𝜃 + cos⁡〖2 𝜃〗 = 1, the value of sin^2⁡𝜃 + sin^2⁡𝜃 is (a) −1 (b) 0 (c) 1 (d) 2 Given 𝑐𝑜𝑠⁡𝜃 + 〖𝑐𝑜𝑠〗^2⁡𝜃 = 1 𝑐𝑜𝑠⁡𝜃 = 1 − 〖𝒄𝒐𝒔〗^𝟐⁡𝜽 𝑐𝑜𝑠⁡𝜃 = 〖𝑠𝑖𝑛〗^2⁡𝜃 〖𝒔𝒊𝒏〗^𝟐⁡𝜽 = 𝒄𝒐𝒔⁡𝜽 Now, 〖𝑠𝑖𝑛〗^2⁡𝜃 + 〖𝑠𝑖𝑛〗^4⁡𝜃 = 𝒄𝒐𝒔⁡𝜽 + 〖𝒄𝒐𝒔〗^𝟐⁡𝜽 = 1 So, the correct answer is (c)
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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo