Do tứ giác ABCP nội tiếp nên ta có:
+ = 180o (1)
Ta lại có: + = 180o (2)
(hai góc trong cùng phía tạo bởi cát tuyến CB và AB // CD)
Từ (1) và (2) suy ra: =
Vậy ABCP là hình thang cân, suy ra AP = BC (3)
nhưng BC = AD (hai cạnh đối đỉnh của hình bình hành) (4)
Từ (3) và (4) suy ra AP = AD.
1. Someone has stolen by bicycle.
➩ My bicycle has been stolen
2. If he doesn't work hard, he will not pass his exam.
=> Unless he work hard, he will not pass his exam 3. I don't have free time, so I can't go some where.
➩ If I had free time, I could go some where
4. Vy ate a lot last night, so she had a stomachache.
➩ Because Vy ate a lot last night, she had a stomachache.
5. My mother had gone to work before I got up.
➩ After my mother had gone work, I got up