F2 Maths
2008-08-25 12:08 am
The height of triangle ABC is h (m). AB=100m, angle A=40 degrees and angle B=30 degrees. Find the value of h, correct to 1 decimal place.
回答 (1)
2008-08-25 2:36 am
✔ 最佳答案
Let CM = h, where CM is perpendicular to AB.So h/AM = tan 40 or AM = h tan 40 ............(1)
h/MB = tan 30 or MB = h tan 30.............(2)
But AM + MB = AB = 100. Therefore, (1) + (2) = 100
h tan 40 + h tan 30 = 100
h = 100/(tan 40 + tan 30) = 100/(0.8391 + 0.5774) = 100/1.4165 = 70.6m ( to 1 dec. place).
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