<prompt> Eneo la trapezoid ABCD ni 164 textcm2. Mwinuko ni 8 textcm, AB ni 10 textcm, na CD ni 17 textcm. BC ni nini, kwa sentimita? asy AMC8 2003 21 Tatizo saizi inchi 2, inchi 1;kuchora0,0--31,0--16,8--6,8--mzunguko;chora11,8--11,0, aina ya mstari8 4;chora11,1--12,1--12,0;leboA, 0,0, SW;leboD, 31,0, SE;leboB, 6,8, NW;leboC, 16,8, NE;lebo10, 3,5, W;lebo8, 11,4, E;lebo17, 22.5,5, E;asy  <response>: Weka miguu ya miinuko kutoka B na C kama E na F mtawalia. Kwa kuzingatia pembetatu za kulia AEB na DFC, AE sqrt102 - 82 sqrt36 6text cm, na FD sqrt172-82 sqrt225 15maandishi cm. Kwa hivyo eneo la pembetatu AEB ni frac1268 24 text cm2, na eneo la pembetatu DFC ni left frac12kulia 158 60 maandishi cm2. Mstatili BCFE una eneo 164 - 24 60 80 maandishi cm2. Kwa sababu BE CF 8 cm, inafuata kwamba BC 10text cm. asy AMC8 2003 21 Suluhisho saizi inchi 2, inchi 1;kuchora0,0--31,0--16,8--6,8--mzunguko;chora6,8--6,0, aina nyekunduya mstari8 4;chora16,8--16,0, aina nyekunduya mstari8 4;leboA, 0,0, SW;leboD, 31,0, SE;leboB, 6,8, NW;leboC, 16,8, NE;leboE, 6,0, S;leboF, 16,0, S;lebo10, 3,5, W;lebo8, 6,4, E, nyekundu;lebo8, 16,4, E, nyekundu;lebo17, 22.5,5, E;asy 