Question

数学达人请入~ 高1数学题求解

已知tan色塔=-3/4，求2+sin色塔cos色塔-cos平方色塔的值
公式+答案 拜求

Answer 1

2+sin色塔cos色塔-cos平方色塔
=1+sin色塔cos色塔+sin平方色塔;由tan色塔=-3/4,得
=1/4+sin平方色塔;由tan色塔=cos色塔/sin色塔，sin平方色塔+cos平方色塔=1得
=21/20

Answer 2

2+sin色塔cos色塔-cos平方色塔=3/2+(sin2a-cos2a)/2=3/2+(2tana/(1+tan^2a)-(1-tan^2a)/(1+tan^2a)/2(万能公式）=7/25
万能公式见http://baike.baidu.com/image/caae68099d59269c2eddd480

Answer 3

2+sin色塔cos色塔-cos平方色塔的值 你确定是2+而不是2×？

Answer 4

2+sinθcosθ-cos^2(θ)
=2+sinθcosθ(1-cosθ/sinθ)
=2+1/( ( sin^2(θ) + cos^2(θ) ) / sinθcosθ ) (1-cosθ/sinθ)
=2+1/( sinθ/cosθ +cosθ/sinθ ) (1-cosθ/sinθ)
=2+1/( tanθ + 1/tanθ ) (1- 1/tanθ)
=2+1/(-3/4-4/3) (1+4/3)
=2-(12/25)(7/3)
=22/25

Answer 5

化成2西塔