could someone help me prove this trig identity sin(pi/2 +x) = cos(x)?
回答 (4)
2016-07-04 7:06 pm
Trigonometric identity : sin(A - B) = sin(A) cos(B) - cos(A) sin(B)
Sin[(π/2) - x]
= sin(π/2) cos(x) - cos(π/2) sin(x)
= 1 × cos(x) - 0 × sin(x)
= cos(x)
Sin[(π/2) - x]
= sin(π/2) cos(x) - cos(π/2) sin(x)
= 1 × cos(x) - 0 × sin(x)
= cos(x)
2016-07-04 7:56 pm
sin(π/2 + x) = sin(π/2)cos(x) + cos(π/2)sin(x)
= 1·cos(x) + 0·sin(x)
= cos(x)
= 1·cos(x) + 0·sin(x)
= cos(x)
2016-07-04 7:06 pm
Hint: sin(A + B) = sinA cosB + cosA sinB
2016-07-04 7:00 pm
bonjour
收錄日期: 2021-04-18 15:15:04
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https://hk.answers.yahoo.com/question/index?qid=20160704105955AAQlCdN