(1-tanα)/(1+tanα)=3-2√2 求[(sinα+cosα)^2-1]/(cotα-sinα乘cosα) 的值
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(1-tanα)/(1+tanα)=3-2√2 求[(sinα+cosα)^2-1]/(cotα-sinα乘cosα) 的值
(1-tanα)/(1+tanα)=3-2√2 求[(sinα+cosα)^2-1]/(cotα-sinα乘cosα) 的值
(1-tanα)/(1+tanα)=3-2√2 求[(sinα+cosα)^2-1]/(cotα-sinα乘cosα) 的值
[(sinα+cosα)^2-1]/(cotα-sinα乘cosα)
=2sinacosa/(cota-sinacoa)
=2/[(csca)^2-1]
=2(tana)^2
又由
(1-tanα)/(1+tanα)=3-2√2
1-tana=(3-2√2)+(3-2√2)tana
即
(2√2-4)tana=2-2√2
tana=(2-2√2)/(2√2-4)
所以原式=1
(1-tanα)/(1+tanα)=3-2√2
(1-tanα)=(1+tanα)(3-2√2)
tanα=根号2/2
[(sinα+cosα)^2-1]/(cotα-sinαcosα)
=[sin^2α+cos^2α+2sinαcosα-1]/(cosα/sinα-sinαcosα)
=[1+2sinαcosα-1]/(cosα/sinα-sinαco...
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(1-tanα)/(1+tanα)=3-2√2
(1-tanα)=(1+tanα)(3-2√2)
tanα=根号2/2
[(sinα+cosα)^2-1]/(cotα-sinαcosα)
=[sin^2α+cos^2α+2sinαcosα-1]/(cosα/sinα-sinαcosα)
=[1+2sinαcosα-1]/(cosα/sinα-sinαcosα)
=2sinαcosα/(cosα/sinα-sinαcosα)
=2sin^2αcosα/(cosα-sin^2αcosα)
=2sin^2α/(1-sin^2α)
=2sin^2α/(cos^2α)
=2tan^2α
=2*(根号2/2)^2
=1
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[(sinα+cosα)^2-1]/(cotα-sinαcosα) ]
=2sinacosa/(cosa/sina-sinacosa)
=2/(1/sin²a -1)
=2/(cos²a/sin²a)
=2sin²a/cos²a
=2tan²a
由(1-tanα)/(1+tanα)=3-2√...
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[(sinα+cosα)^2-1]/(cotα-sinαcosα) ]
=2sinacosa/(cosa/sina-sinacosa)
=2/(1/sin²a -1)
=2/(cos²a/sin²a)
=2sin²a/cos²a
=2tan²a
由(1-tanα)/(1+tanα)=3-2√2得
1-tana=3-2√2(1+tana)
1-tana=3-2√2+(3-2√2)tana
得√2-1=(2-√2)tana
所以tana=(√2-1)/(2-√2)=(√2-1)(2+√2)/2=(2√2+2-√2-2)/2=√2/2
所以
[(sinα+cosα)^2-1]/(cotα-sinαcosα) ]
=2tan²a
=2(√2/2)²
=1
收起