求值题.thanks.14.求值：sin50°×〔 - 知识问答

求值题.thanks.14.求值：sin50°×〔1＋（根号3）tan10°〕

1个回答

sin50°[1+(√3)×tan10°]
=sin50×[(√3)sin10+cos10]/cos10
=(sin50/cos10)×2×(cos30sin10+cos10sin30)
=(sin50/cos10)×2×sin40
=2×sin50×cos50/cos10
=sin100/cos10
=cos10/cos10
=1

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