If sin θ – cos θ = 0, then the value of (sin 4 θ + cos 4 θ) is

(A) 1 

(B) 3/4 

(C) 1/2     

(D) 1/4

Slide26.JPG

Slide27.JPG

Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class


Transcript

Question 16 If sin θ – cos θ = 0, then the value of (sin4 θ + cos4 θ) is (A) 1 (B) 3/4 (C) 1/2 (D) 1/4 Given sin θ – cos θ = 0 sin θ = cos θ This can only happen if θ = 45° Now, sin4 θ + cos4 θ = sin4 45° + cos4 45° = (1/√2)^4+(1/√2)^4 = 2 × (𝟏/√𝟐)^𝟒 = 2 × [(1/√2)^2 ]^2 = 2 × [1/2]^2 = 2 × 1/4 = 𝟏/𝟐 So, the correct answer is (C)

Ask a doubt
Davneet Singh's photo - Co-founder, Teachoo

Made by

Davneet Singh

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.