Question

已知如图,在△ABC中,AB=AC,点M,N在AC上,且MB=MN,∠ABN=∠MBC,求∠NBC的度数

Answer 1

∠用"代替

MN=MB

"MBN="MNB

"MNB="A + "ABN

"MBN="A + "ABN

∠ABN=∠MBC

"ABC="ABN + "MBN +"MBC = 3"ABN + "A

AB=AC

"ABC = "C

3角型内角和为180

"A + "ABC + "C = "A + 2"ABC = "A + 2*(3"ABN + "A) = 6"ABN + 3"A =180

2"ABN + "A = 60

"A = "MNB - "ABN

2"ABN + "MNB - "ABN = "ABN + "MNB = "MBC + "MBN = 60 = ∠NBC

不会打因为所以.只好这样啦~

应该这样吧~如果有更简单的方法记得打出来啊~