4.
如图所示,在⊙O中,直径AB⊥弦EF,垂足为P,AP=1cm,BP=3cm,EF等于( )
| A. | 2$\sqrt{3}$cm | B. | $\sqrt{3}$cm | C. | 2cm | D. | 4cm |
2.
如图,∠1的正切值为( )
0 308985 308993 308999 309003 309009 309011 309015 309021 309023 309029 309035 309039 309041 309045 309051 309053 309059 309063 309065 309069 309071 309075 309077 309079 309080 309081 309083 309084 309085 309087 309089 309093 309095 309099 309101 309105 309111 309113 309119 309123 309125 309129 309135 309141 309143 309149 309153 309155 309161 309165 309171 309179 366461
| A. | $\frac{1}{2}$ | B. | $\frac{1}{3}$ | C. | $\frac{\sqrt{10}}{10}$ | D. | $\frac{3\sqrt{10}}{10}$ |