<prompt> Mistari l na k ni sambamba kwa kila mmoja. mangle A 120circ, na mangle C 80circ. Ni idadi gani ya digrii katika mangle B?asyukubwa 100; h halisi 1.2; currentpen fontsize10pt;drawLebol,Relative1,0,0--1,0,E;kuchoraLebok,Jamaa1,0,-h--1,-h,E;chora0,-h--h2cos150pi180,sin150pi180 0,-h;choraLeboC,Jamaa1,0,0--hsqrt32cos-120pi180,sin-120pi 180, W;leboA,0,0,N; leboB,0,-h,S;lebo120circ,0,0,SE; lebo80circ,hsqrt32cos-120pi180,sin-120pi1800.1,0,E;asy  <response>: Tunachora sehemu overlineCD kama inavyoonyeshwa sambamba na mistari l na k.asyukubwa 200; h halisi 1.2; currentpen fontsize10pt;drawLebol,Relative1,0,0--1,0,E;kuchoraLebok,Jamaa1,0,-h--1,-h,E;chora0,-h--h2cos150pi180,sin150pi180 0,-h;choraLeboC,Jamaa1,0,0--hsqrt32cos-120pi180,sin-120pi 180, W;leboA,0,0,N; leboB,0,-h,S;lebo120circ,0,0,SE;jozi D hsqrt32cos-120pi180,sin-120pi180 2,0;kuchoraD -- D-2,0;nukta D;leboD,D,E;asyKwa kuwa overlineCDparallel l, tuna angle ACD 180circ - angle A 60circ, hivyo angle DCB angle ACB - angle ACD 80 circ - 60 circ 20circ. Kwa kuwa overlineCDparallel k, tuna angle B 180circ - angle DCB 160circ. 