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2 năm trước
Tia sáng SI đến 1 gương phẳng có tia phản xạ IR. Cho biết tia SI hợp với gương phẳng góc a= 60 độ , tia IR có phương thẳng đứng . Hãy tìm góc hợp bởi gương với phương ngang
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