所以\sin\theta ={-2\over \sqrt{1+(-2)^2} } =-{2\sqrt{5}\over 5 } ,\cos\theta ={1\over \sqrt{1+(-2)^2} } ={\sqrt{5}\over 5 } , 则\sin\theta \cos\theta =-{2\sqrt{5}\over 5 } \times {\sqrt{5}\over 5 }=-{2\over 5} 。 故本题正确答案为-{2\over 5}...
Hint: Take $5\theta $ as $3\theta +2\theta $. Now use trigonometry identity of $\sin \left( A+B \right),\sin 3\theta ,\cos 3\theta ,\sin 2\theta ,\cos 2\theta $ to solve it further and get the value of $\sin 5\theta $ in terms of $\...
曲线\rho =\sin \theta 与\rho =\cos \theta \left( \rho >0,0\leqslant \theta \leqslant \dfrac{ \pi }{2} \right)分别化为{{\rho }^{2}}=\rho \sin \theta ,{{\rho }^{2}}=\rho \cos \theta .可得直角坐标方程为:{{x}^{2}}+{{y}^{2}}=y,{{x}^{2}}+{{y}^{2}}...
Viewed173 times Letpθbe a family of distributions given by pθ=(sinθ)x(cos2θ)2xsinθcos defined forx∈Z+x∈Z+andθ∈[a,π2]θ∈[a,π2], whereaais some known constant,θθis the unknown parameter. Here the density is defined with respect to t...
)) dxIn=∫0π/2cos(cos(…(cos⏟n times(x))…)) dx for all n∈Nn∈N. 0 limx→0(ex−e−x−2ln(1+x)xsin(x))limx→0(ex−e−x−2ln(1+x)xsin(x)) : 11 or −1−1? 0 how to apply "εε- δδ" definition of limit H...
Answer to: Simplify: 1) \frac{-\sin(-x) \cos x \sec x \csc x \tan x}{\cot x} \\2) \frac{1 + \tan^2 \theta}{\csc^2 \theta} + \sin^2 \theta +...
1、已知$\cos \theta =- \frac{3}{5}$,$\theta \in(\frac{\pi}{2}, \pi)$,求$\sin(\theta + \fr
1 已知角\theta 的终边经过点P(-3a,\, 4a),(1)当a= 1时,求\sin \theta -2\cos \theta 的值;(2)若\sin \theta = -\dfrac{4}{5},求3\tan \theta + 5\cos \theta 的值. 2已知角的终边经过点,且.(1)求,的值;(2)求的值. 3已知角的终边经过点,(Ⅰ)求和的值;(Ⅱ)若,求...
\therefore \frac{\cos \theta}{\sin \theta}=3 \cos \theta,可得: \sin \theta=\frac{1}{3} \therefore \cos \theta=\sqrt{1-\sin ^{2} \theta}=\frac{2 \sqrt{2}}{3} \therefore \sin 2 \theta=2 \sin \theta \cos \theta=2 \times \frac{1}{3} \times \frac{2 \sqrt...
利用辅助角公式可得:\sin \theta -\cos\theta =\sqrt{2} \sin(\theta -{\pi \over 4} )={\sqrt{6} \over 3} ,所以\sin (\theta -{\pi \over 4} ) ={\sqrt{3} \over 3} ,所以\cos(2\theta-{\pi \over 2} ) =1-2\sin ^{2}(\theta-{\pi \over 4} )=1-2\times {1\...