Chuong I 2 Ti so luong giac cua goc nhon Bai tap thuc te bang Tieng Anh

<span class='text_page_counter'>(1)</span>10 bài tập ứng dụng tỉ số lượng giác trong thực tế (lớp 9) – Đoan Hiền 1. A ladder 5m long, leaning against a vertical wall makes an angle of 65˚ with the ground. a) How high on the wall does the ladder reach? b) How far is the foot of the ladder from the wall? c) What angle does the ladder make with the wall?. 2. Two towers face each other separated by a distance d = 30 m. As seen from the top of the first tower, the angle of depression of the second tower's base is 60o and that of the top is 30o. What is the height (in meters) of the second tower? (Hint: 34.64m). 3. Two men on opposite sides of a TV tower of height 20 m notice the angle of elevation of the top of this tower to be 45o and 60o respectively. Find the distance (in meters) between the two men. (Hint: 31.55m) 4. Two men on the same side of a tall building notice the angle of elevation to the top of the building to be 30o and 60orespectively. If the height of the building is known to be h =110 m, find the distance (in meters) between the two men. (Hint: 127.02m). 5. A pole of height h = 50 ft has a shadow of length l = 50.00 ft at a particular instant of time. Find the angle of elevation (in degrees) of the sun at this point of time. (Hint: 45O).

<span class='text_page_counter'>(2)</span> 6. You are stationed at a radar base and you observe an unidentified plane at an altitude h = 1000 m flying towards your radar base at an angle of elevation = 30o. After exactly one minute, your radar sweep reveals that the plane is now at an angle of elevation = 60o maintaining the same altitude. What is the speed (in m/s) of the plane? (Hint: 19.25 m/s) 7. A ship of height h = 21 m is sighted from a lighthouse. From the top of the lighthouse, the angle of depression to the top of the mast and the base of the ship equal 30o and 45o respectively. How far is the ship from the lighthouse (in meters)? (Hint: 49.69m) 8. A flat 12 foot plank rests with one end on the ground and the other end upon a 4 foot ledge. (a) How far from the base of the ledge is the far end of the plank? (11.3 ft) (b) What is the angle of elevation? (19.46o) 9. Some wire connects from a pole to point on the ground at an angle of depression of 80º. On the ground, the wire is 4.5 ft from the pole. (a) How much wire is used? (29.5ft) (b) How high up the pole is the wire connected? (25.52 ft). 10. At a certain distance, the angle of elevation to the top of a building is 60º. From 40 feet further back, the angle of elevation is 45º . Find the height of the building. (Hint: 94.64 ft).

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