百度试题 结果1 题目若\(\tan \alpha = 2\),则\(\sin \alpha \cos \alpha\)的值为: A. \(\frac{1}{5}\) B. \(\frac{2}{5}\) C. \(\frac{4}{5}\) D. \(\frac{3}{5}\) 相关知识点: 试题来源: 解析 C 反馈 收藏
\tan\alpha=2,求值: (1)\frac{3\sin\alpha+\cos\alpha}{3\cos\alpha+\sin\alpha} (2)\frac{\sin^{3}\alpha+2\cos^{3}\alpha}{\sin^{3}\alpha-2\cos^{3}\alpha} (3) 2\sin^{2}\alpha+3\sin\alpha\cdot\cos\alpha+5\cos^{2}\alpha 相关知识点: 试题来源: 解析 . 综上...
(2)cos\alpha =2cos^2\frac{\alpha }{2}-1,所以cos\frac{\alpha }{2}=\pm \sqrt{\frac{1+cos\alpha }{2}}。 (3)tan\frac{\alpha }{2} =sin\frac{\alpha }{2}\div cos\frac{\alpha }{2}=\pm \sqrt{\frac{1-cos\alpha }{1+cos\alpha }}。 故本题的答案为(1)\pm \s...
(1)解:原式\(=\dfrac{tan\alpha-1}{1+2tan\alpha}=\dfrac{1}{5}\);(2)原式\(=\dfrac{sin^{2}\alpha+sin\alpha cos\alpha+3cos^{2}\alpha}{sin^{2}\alpha+cos^{2}\alpha}=\dfrac{tan^{2}\alpha+tan\alpha+3}{tan^{2}\alpha+1}=\dfrac{9}{5}\);(3)原式\(=\dfrac{sin...
Free ALLEN Course Text SolutionVerified by Experts The correct Answer is:B 1| ShareSave Answer Step by step video, text & image solution for If sinalpha+cosalpha=(1)/(5), find tan((alpha)/(2)). by Maths experts to help you in doubts & scoring excellent marks in Class 11 exams.Upda...
百度试题 结果1 题目\( \tan \alpha =2\)且\(\dfrac{ \cos \alpha }{ \sin \alpha }=\dfrac{1}{3}\).相关知识点: 试题来源: 解析 × 反馈 收藏
D. \(2\tan 2α\) 相关知识点: 试题来源: 解析 C 解:y= \dfrac {2\sin 2α}{1+\cos 2\alpha }= \dfrac {4\sin α\cos α}{2\cos ^{2}\alpha }= \dfrac {2\sin α}{\cos \alpha }=2\tan α. 故选:C.利用二倍角公式对所求关系式化简即可.本题考查二倍角公式的...
\angle\alpha的终边经过下列各点,求 \sin\alpha、 \cos\alpha和 \tan\alpha.(1X-4,-3);(2)(\frac{\sqrt{3}}{2},-\frac{1}{2});(3X-3\sqrt{3},3);(4)(2,2\sqrt{3}).相关知识点: 试题来源: 解析 (1)的终边经过时,有, , 根据三角函数的定义有: ,,, 综上,结论为:,,; (...
已知\(\alpha\)为第二象限角,则\(\cos \alpha \cdot \sqrt{1+ \tan ^{2} \alpha }+ \sin \alpha \sqrt{1+\dfrac{1}{ \tan ^{2} \alpha }}=\)___. 相关知识点: 试题来源: 解析 \(0\) 原式\(= \cos \alpha \sqrt{1+\dfrac{ \sin ^{2} \alpha }{\cos ^{2} ...
(1)(sina+cosa)/(sina-cosa)=(tana+1)/(tana-1)=(2+1)/(2-1)=3综上,结论是:(sinα+cosα)/(sinα-cosα)=3(2)(2sin^2a-3cos^2a)/(sin^2a+4cos^2a)=(2tan^2α-3)/(tan^2α-4)=(2*4-3)/(4-4)=5/8综上,结论是:(2sin^2α-3cos^2α)/(sin^2α+4cos^2α)=5...