13.已知双曲线$\frac{{x}^{2}}{{a}^{2}}$-$\frac{{y}^{2}}{{b}^{2}}$=1(a>0,b>0)的左、右焦点分别为F1,F2,在左支上过F1的弦AB的长为5,若2a=8,那么△ABF2的周长是( )
0 224366 224374 224380 224384 224390 224392 224396 224402 224404 224410 224416 224420 224422 224426 224432 224434 224440 224444 224446 224450 224452 224456 224458 224460 224461 224462 224464 224465 224466 224468 224470 224474 224476 224480 224482 224486 224492 224494 224500 224504 224506 224510 224516 224522 224524 224530 224534 224536 224542 224546 224552 224560 266669
| A. | 16 | B. | 18 | C. | 21 | D. | 26 |