已知向量a=(cosα,-2),b=(sinα,1),若a∥b,则tan(α- π/4)= (A)1/3 (B)3 (C)-1/3 (D)-3
已知向量a=(cosα,-2),b=(sinα,1),若a∥b,则tan(α- π/4)= (A)1/3 (B)3 (C)-1/3 (D)-3
数学人气:798 ℃时间:2020-04-12 03:59:03
优质解答
由于a∥b,1/-2=sina/cosa=tana,tan(a-π/4)=(tana-1)/(1+tana)=-3/2/1/2=-3 选D
我来回答
类似推荐
猜你喜欢
- 1下列物质进行一氯取代反应后,只能生成四种沸点不同产物的烃是( ) A.(CH3)2CHCH2CH2CH3 B.(CH3CH2)2CHCH3 C.(CH3)2CHCH(CH3)2 D.(CH3)3CCH2CH3
- 2She looks so much( )her mother
- 3Can you tell me what is the relation between you and the owner?
- 4甲数是乙数的2/3,乙数是丙数的3/4,甲、乙、丙的和是216,甲、乙、丙各是多少?
- 5It really took him him__to draw the nice horse.A.long time B.some time
- 6面对未来,今天人类对待战争应持有怎样的态度?
- 7______boy in white shirt is my classmate.A.A B.The C./
- 81.一个自然数,被8除余1,所得的商被8除也余1,再把第2次所得的商被8除结果余7,最后所得的商是A;又知这个自然数被17除余4,所得的商被17除余15,最后得到的商是A的2倍,那么这个自然数是?
- 9尊严读后感怎么办
- 10she is on her w to the park then she t out a pen and some paper