2026年南方凤凰台5A新考案高中数学二轮基础版


注:目前有些书本章节名称可能整理的还不是很完善,但都是按照顺序排列的,请同学们按照顺序仔细查找。练习册 2026年南方凤凰台5A新考案高中数学二轮基础版 答案主要是用来给同学们做完题方便对答案用的,请勿直接抄袭。



《2026年南方凤凰台5A新考案高中数学二轮基础版》

1. (人 A 必一 P218 例 3 改)若 $\alpha \in \left(\dfrac{\pi}{2}, \pi\right), \sin \alpha = \dfrac{3}{5}$,则 $\tan\left(\alpha + \dfrac{\pi}{4}\right) =$(
A
)

A.$\dfrac{1}{7}$
B.$7$
C.$-\dfrac{1}{7}$
D.$-7$
答案: 1.A 【解析】由$\alpha \in \left( \frac{\pi}{2}, \pi \right)$,$\sin \alpha = \frac{3}{5}$,得$\tan \alpha = - \frac{3}{4}$,则$\tan \left( \alpha + \frac{\pi}{4} \right) = \frac{\tan \alpha + 1}{1 - \tan \alpha} = \frac{1}{7}$。
2. (人 A 必一 P217 练习 5 改)设 $0 < \alpha < \dfrac{\pi}{2}, -\dfrac{\pi}{2} < \beta < 0$,且 $\sin \alpha = \dfrac{\sqrt{10}}{10}, \sin \beta = -\dfrac{\sqrt{5}}{5}$,则 $\alpha - \beta =$(
B
)

A.$\dfrac{\pi}{6}$
B.$\dfrac{\pi}{4}$
C.$\dfrac{\pi}{3}$
D.$\dfrac{3\pi}{4}$
答案: 2.B 【解析】因为$0 < \alpha < \frac{\pi}{2}$,$ - \frac{\pi}{2} < \beta < 0$,所以$\cos \alpha = \sqrt{1 - \sin^{2} \alpha} = \sqrt{1 - \left(\frac{1}{5}\right)} = \frac{2\sqrt{5}}{5}$,$\cos \beta = \sqrt{1 - \sin^{2} \beta} = \sqrt{1 - \left(-\frac{1}{5}\right)} = \frac{2\sqrt{5}}{5}$,$0 < \alpha - \beta < \pi$,$\cos (\alpha - \beta) = \cos \alpha \cos \beta + \sin \alpha \sin \beta = \frac{2\sqrt{5}}{5} × \frac{2\sqrt{5}}{5} + \frac{\sqrt{5}}{5} × \left(-\frac{\sqrt{5}}{5}\right) = \frac{3}{5}$,此部分大模型计算有误,以OCR为准,$0 < \alpha - \beta < \pi$,$\cos (\alpha - \beta) = \cos \alpha \cos \beta + \sin \alpha \sin \beta = \frac{3\sqrt{10}}{10} × \frac{2\sqrt{5}}{5} + \frac{\sqrt{10}}{10} × \left(-\frac{\sqrt{5}}{5}\right) = \frac{\sqrt{2}}{2}$,所以$\alpha - \beta = \frac{\pi}{4}$。
3. (人 A 必一 P223 练习 5 改)下列各式的值为 $\dfrac{1}{2}$ 的是(
B
)

A.$\sin 15^{\circ} \sin 75^{\circ}$
B.$\cos^2 \dfrac{\pi}{6} - \sin^2 \dfrac{\pi}{6}$
C.$\dfrac{\tan 30^{\circ}}{1 - \tan^2 30^{\circ}}$
D.$\sqrt{\dfrac{1 + \cos 60^{\circ}}{2}}$
答案: 3.B 【解析】对于A,$\sin 15^{\circ} \sin 75^{\circ} = \sin 15^{\circ} \cos 15^{\circ} = \frac{1}{2} × 2 \sin 15^{\circ} \cos 15^{\circ} = \frac{1}{2} \sin 30^{\circ} = \frac{1}{4}$,故A错误;对于B,$\cos^{2} \frac{\pi}{6} - \sin^{2} \frac{\pi}{6} = \cos \frac{\pi}{3} = \frac{1}{2}$,故B正确;对于C,原式$= \frac{1}{2} × \frac{2 \tan 30^{\circ}}{1 - \tan^{2} 30^{\circ}} = \frac{1}{2} \tan 60^{\circ} = \frac{\sqrt{3}}{2}$,故C错误;对于D,原式$= \cos 30^{\circ} = \frac{\sqrt{3}}{2}$,故D错误。
4. (人 A 必一 P223 练习 2 改)若 $\cos \theta = -\dfrac{3}{5}, \theta \in \left(\dfrac{\pi}{2}, \pi\right)$,则 $\sin\left(2\theta + \dfrac{\pi}{4}\right) =$
$ - \frac{31 \sqrt{2}}{50}$
答案: 4.$ - \frac{31 \sqrt{2}}{50}$ 【解析】因为$\cos \theta = - \frac{3}{5}$,$\theta \in \left( \frac{\pi}{2}, \pi \right)$,所以$\sin \theta = \sqrt{1 - \cos^{2} \theta} = \frac{4}{5}$,所以$\sin 2 \theta = 2 \sin \theta \cos \theta = - \frac{24}{25}$,$\cos 2 \theta = 1 - 2 \sin^{2} \theta = - \frac{7}{25}$,所以$\sin \left( 2 \theta + \frac{\pi}{4} \right) = \frac{\sqrt{2}}{2} \left( \sin 2 \theta + \cos 2 \theta \right) = \frac{\sqrt{2}}{2} × \left( - \frac{24}{25} - \frac{7}{25} \right) = - \frac{31 \sqrt{2}}{50}$。
5. (2025·全国Ⅱ卷)已知 $\alpha \in (0, \pi), \cos \dfrac{\alpha}{2} = \dfrac{\sqrt{5}}{5}$,则 $\sin\left(\alpha - \dfrac{\pi}{4}\right) =$(
D
)

A.$\dfrac{\sqrt{2}}{10}$
B.$\dfrac{\sqrt{2}}{5}$
C.$\dfrac{3\sqrt{2}}{10}$
D.$\dfrac{7\sqrt{2}}{10}$
答案: 5.D 【解析】由题知$\cos \alpha = 2 \cos^{2} \frac{\alpha}{2} - 1 = 2 × \left( \frac{\sqrt{5}}{5} \right)^{2} - 1 = - \frac{3}{5}$,因为$0 < \alpha < \pi$,所以$\frac{\pi}{2} < \alpha < \pi$,则$\sin \alpha = \sqrt{1 - \cos^{2} \alpha} = \sqrt{1 - \left( - \frac{3}{5} \right)^{2}} = \frac{4}{5}$,则$\sin \left( \alpha - \frac{\pi}{4} \right) = \sin \alpha \cos \frac{\pi}{4} - \cos \alpha \sin \frac{\pi}{4} = \frac{4}{5} × \frac{\sqrt{2}}{2} - \left( - \frac{3}{5} \right) × \frac{\sqrt{2}}{2} = \frac{7 \sqrt{2}}{10}$。

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