ans
012487
真

012488
$[0,1]$

012489
$6$

012490
$\dfrac\pi 6$或$\dfrac{5\pi}6$

012491
$2$

012492
$(3,0)$

012493
$12$

012494
$\dfrac 54$或$\dfrac 53$

012495
$4+2\sqrt{3}$

012496
$243$

012497
$2018$

012498
$(-\dfrac 34,0)$

012499
C

012500
D

012501
A

012502
B

012503
(1) $\dfrac{2\pi}3$; (2) $\sqrt{3}$

012504
(1) $4\sqrt{2}\pi$; (2) 证明略, 角的大小为$\arccos\dfrac{7\sqrt{5}}{20}$

012505
(1) $1965$万元; (2) $22.5$万台; (3) 产量均为$30$万台, 利润分别为$840$万元与$860$万元

012506
(1) $2\sqrt{2}+2$; (2) $\pm \dfrac{\sqrt{14}}2$; (3) $\sqrt{2}$或$\sqrt{3}$或$\sqrt{\dfrac{1+\sqrt{17}}2}$

012507
(1) $[-\dfrac{\sqrt[3]{2}}2,+\infty)$; (2) $(-2,-1)$; (3) $a=-2$