证明:sin^{2}θ+cos^{2}θ=(BC/AB)^{2}+(AC/AB)^{2}=[BC^{2}+AC^{2}]/AB^{2}=1(根据勾股定理) (2)tanθ=sinθ/cosθ 证明:sinθ/cosθ=(BC/AB)/(AC/AB)=BC/AC=tanθ (3)cot=cosθ/sinθ 证明与(2)类似 (4)cotθ=1/tanθ,cscθ=1/sinθ,secθ=1/cosθ 根据它们的定...
关于三角函数有如下的公式:\sin (\alpha + \beta )=\sin \alpha \cos \beta + \cos \alpha \sin \beta ①
关于三角函数有如下公式:\sin (\alpha + \beta )= \sin \alpha \cos \beta + \cos \alpha \sin \beta ,
这个cot的发音就类似 cos 和 tan 的结合了。[kəu'tændgent],大概【扣瘫真特】吧。 Δ 叼它就算了。。。这个我念了好几年的【der他】不过正确的发音应该是['deltə],【呆偶他】? α 阿花!!! 这个其实就是希腊字母Alpha啦,['...
Find the value of sin (alpha - beta), cos (alpha -beta) and tan (alph... 07:26 If A and B are acute angles, find (A+B) given sin A = (1)/(sqrt5) ,... 06:39 If A and B are acute angles, find (A+B) given tan A = (5)/(6), tan ... 02:36 Given that tan ...
Why is cosα−cosβ=−2sin(2α+β)sin(2α−β)? https://www.quora.com/Why-is-cos-alpha-cos-beta-2-sin-frac-alpha+-beta-2-sin-frac-alpha-beta-2 To show why, our goal will be to manipulate t...
(a+B)sin a cos 8+cos a sin B ---①sin(a-B)=sin a cos B-cos asin B ---②由①+② 得sin(a+B)+sin (a-B)=2 sin acos B ---③令a+B=Aa-B= B 有A+B A-B=22代入③得 A+B A-B sin A+sin B=2 sin COS22.(1)利用上述结论,试求sin15+sin75的值。(2)类比上述推证...
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关于公式$\sin \left(\alpha +\beta \right)=\sin \alpha \cos \beta +\cos \alpha \sin \beta
微判断微判断(1) \$\sin ( \alpha - \beta ) = \sin \alpha \cos \alpha - \cos \beta \sin \beta\$ 微判断微判断(1)微判断(1) \$\sin ( \alpha - \beta ) = \sin \alpha \cos \alpha - \cos \beta \sin \beta\$ 微判断(1) \$\sin ( \alpha - \beta ) = \sin \...