Question

几道初中数学题 有难度 高手进 在线等！！

两道解答题，一道填空题，填空题是第八题 题目如图：http://hi.baidu.com/%C4%E3tm%B1%F0%D5%D2pia/album/item/2270c427f2655cee4623e882.html
http://hi.baidu.com/%C4%E3tm%B1%F0%D5%D2pia/album/item/2270c427f2655cee4623e882.html#IMG=6d552e4124d66606510ffe81
http://hi.baidu.com/%C4%E3tm%B1%F0%D5%D2pia/album/item/2270c427f2655cee4623e882.html#IMG=c0ed2ed3bd52e26507088b80

Answer 1

1. 延长AB，交点为D
所以 CD = 7cos 15，BD = 7sin 15
角ACD = 50度
AD = CDtan50 = 7cos15tan50
所以 AB = AD - BD = 7cos15tan50- 7sin 15
2.填空
BC = ABcot a
BD = ABcot b
s = BC - BD = AB(cot a - cot b)
AB = s/(cot a - cot b)

3.AC = 35*40 = 1440
过C做垂线CH
CH = 1440sin 75,AH = 1440cos 75
BH = CH cot 30
AB = BH - AH，自己算去。
过P做AB垂线PM
所以 BM = PMcot 30, AM = PMcot 45 = PM
AB = BM + AM = PMcot 30 + PM
自己算吧