cứuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu ----- Nội dung ảnh ----- 14. Sử dụng định nghĩa các tí số lượng giác của một góc nhọn để chứng minh rằng: Với góc nhọn α tùy ý, ta có a) tg α = \(\frac{sin α}{cos α}\), cotg α = \(\frac{cos α}{sin α}\), tg α.cotg α = 1; b) \(sin^2 α + cos^2 α = 1\).
