\cos 2\alpha =\cos^2\alpha -\sin^2\alpha ,\tan 2\alpha =\frac{2\tan \alpha }{1-\tan^2\alpha },同理,我们可以证得如下三倍角公式:\sin 3\alpha =3\sin\alpha -4\sin^3\alpha ,\cos 3\alpha =___(要求用\cos\alpha 来表示),\tan 3\alpha =___(要求用\tan\alpha 来表示)...
素下斯了实导然层军已解办手一而油难观原海已知sin\alpha =0.8,且\alpha \in (0,\pi),求cos2\alpha ,sin2\alpha . 素下
Answer Step by step video & image solution for cos(alpha/2)+sin(alpha/2)=sqrt(2)(cos3 6^(@)-sin1 8^(@)) by Maths experts to help you in doubts & scoring excellent marks in Class 11 exams. Updated on:21/07/2023 Doubtnut is No.1 Study App and Learning App with Instant Video...
sin(2α)+1 Evaluate (sin(α)+cos(α))2 Quiz Trigonometry (sinα+cosα)2 Similar Problems from Web Search If sinα+cosα=1.2, then what is sin3α+cos3α? https://math.stackexchange.com/questions/2001078/if-sin-alpha-cos-alpha-1-2-then-what-is-sin3-alpha-cos3-alpha Hint :(si...
由\sin \alpha =2\cos \alpha ,得\tan \alpha =2, 所以;\sin \alpha \cos \alpha =\frac{1}{2}\sin 2\alpha =\frac{1}{2}\times \frac{2\tan \alpha }{1+{{\tan }^{2}}\alpha }=\frac{1}{2}\times \frac{2\times 2}{1+4}=\frac{2}{5}. 故答案为:\frac{2}{5}.反馈...
因为锐角\alpha ,所以;\cos \alpha \ne 0, 则\sin \alpha =\frac{1}{2},\cos \alpha =\frac{\sqrt{3}}{2}, 因为0<{}\alpha < {}\frac{ \pi }{2},0<{}\beta < {}\frac{ \pi }{2}, 所以;0<{}\alpha +\beta < {} \pi ,又\cos \left( \alpha +\beta \right)=\frac{1...
limx→4(cosα)x−(sinα)x−cos2αx−4 Step 1: Check the form of the limit First, we substitute x=4 into the numerator: (cosα)4−(sinα)4−cos2α We need to check if this results in 0: cos4α−sin4α−cos2α Using the identity cos4α−sin4α=(cos2α+sin...
Solve 1 2 α cos 2 α + 1 2 α sin 2 α cos 2 α .sin 2 α = 1 cos 2 α .sin 2 α 2+cos 2 α .sin 2 α
(1)降幂公式:sin^2\alpha =___,cos^2\alpha =___;(2)升幂公式:1+cos\alpha =___,1-cos\alpha
解:因为{{\rm \cos }}^{2}α={\rm \sin }α,所以\dfrac{1}{{\rm \sin }α}+{{\rm \cos }}^{4}α= \dfrac{1}{{\rm \sin }α}+{{\rm \sin }}^{2}α= \dfrac{1}{{\rm \sin }α}+1-{{\rm \cos }}^{2}α= \dfrac{1}{{\rm \sin }α}-{\rm \sin...