18.已知抛物线$y=-\frac{3}{16}(x-1)(x-9)$与x轴交于A,B两点,对称轴与抛物线交于点C,与x轴交于点D,⊙C的半径为2,G为⊙C上一动点,P为AG的中点,则DP的最大值为( )
A. | $\frac{7}{2}$ | B. | $\frac{{\sqrt{41}}}{2}$ | C. | $\frac{{\sqrt{34}}}{2}$ | D. | $2\sqrt{3}$ |
16.在△ABC中,$\overrightarrow{BA}$=(cos16°,sin16°),$\overrightarrow{BC}$=(2sin29°,2cos29°),则△ABC面积为( )
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A. | $\frac{\sqrt{2}}{2}$ | B. | $\sqrt{2}$ | C. | $\frac{\sqrt{3}}{2}$ | D. | $\frac{\sqrt{2}}{4}$ |