Cho góc nhọn xOy, trên tia ax lấy điểm A, B sao cho Oa bằng 3cm , OB bằng 5cm trên tia Oy lấy điểm C, D sao cho Oc bằng Oa , Od bằng Ob. Nối AD và BC cắt nhau tại I a, chứng minh góc OAD bằng góc OCB
b, chứng minh IA bằng IC
d, chứng minh OI là tia phân giác của góc xOy

According to the 2008 u.s. census, california had a population of approximately 4 × 10^7 people and florida had a population of approximately 2 × 10^7 people. which of the following is true? a. the population of california was approximately two times the population of florida. b. the population of florida was approximately twenty times the population of california. c. the population of florida was approximately two times the population of california. d. the population of california was approximately twenty times the population of florida.