Explain please?
FALSE!
Remember:
cos (a – b) = cos a cos b + sin a sin b
cos a – cos b = -2 sin ½(a + b) sin ½(a – b)
cos (a – b) ≠ cos a – cos b
cos 255⁰
= cos (300⁰ - 45⁰)
= cos 300⁰ cos 45⁰ + sin 300⁰ sin 45⁰
= ½*½√2 + (-½√3*½√2)
= ¼√2 – ¼√6
= ¼(√2 – √6)
Copyright © 2024 1QUIZZ.COM - All rights reserved.
Answers & Comments
Verified answer
FALSE!
Remember:
cos (a – b) = cos a cos b + sin a sin b
cos a – cos b = -2 sin ½(a + b) sin ½(a – b)
cos (a – b) ≠ cos a – cos b
cos 255⁰
= cos (300⁰ - 45⁰)
= cos 300⁰ cos 45⁰ + sin 300⁰ sin 45⁰
= ½*½√2 + (-½√3*½√2)
= ¼√2 – ¼√6
= ¼(√2 – √6)