Single correct option
In right triangle ABC, angle A = 90°, AB = 9 and AC = 12. D is the foot of the perpendicular from A to BC. Find the length of AD.
- A. 6
- B. 6.5
- C. 7.2
- D. 7.5
Show answer and solution
Answer: (C) 7.2
By Pythagoras, BC = √(9² + 12²) = √225 = 15. The altitude to the hypotenuse in a right triangle satisfies AD = (AB × AC)/BC (since area = ½·AB·AC = ½·BC·AD). AD = (9×12)/15 = 108/15 = 7.2.
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