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At a particular time during the day, owing to the position of the sun, a 6 feet tall man casts a shadow of 4 feet, whereas a pole next to the man casts a shadow of 36 feet. What is the height of the pole?
56 feet
54 feet
63 feet
60 feet
54 feet
Use the ratio of height to shadow. Since the shadow of the pole is 9 times the shadow of the man (36├╖4=9), the height of the pole is also 9 times the height of the man (6├Ч9=54).
Man's height = 6 feet, Man's shadow = 4 feet, Pole's shadow = 36 feet
Shadow┬аof┬аpoleHeight┬аof┬аpoleтАЛ=Shadow┬аof┬аmanHeight┬аof┬аmanтАЛ
Use the ratio of height to shadow. Since the shadow of the pole is 9 times the shadow of the man (36├╖4=9), the height of the pole is also 9 times the height of the man (6├Ч9=54).
Multiplying the man's shadow by the pole's shadow instead of setting up the correct direct proportion ratio of height to shadow.
Step 1: Understand the concept
At the same time of the day, the angle of elevation of the sun is the same for all objects. Thus, the triangles formed by the objects and their shadows are similar, meaning the ratio of height to shadow length is constant.
Shadow1тАЛHeight1тАЛтАЛ=Shadow2тАЛHeight2тАЛтАЛ
Step 2: Set up the proportion
Let the height of the pole be H feet. Given that the man's height is 6 feet, his shadow is 4 feet, and the pole's shadow is 36 feet.
36HтАЛ=46тАЛ
Step 3: Solve for the height of the pole (H)
Cross-multiplying or simplifying the fraction on the right side: 46тАЛ=1.5. Then multiply by 36.
H=36├Ч46тАЛ=36├Ч1.5=54
B is correct because the height of the pole calculated using similar triangles is 54 feet.
Similar triangle principles are widely used in height and distance problems in trigonometry and scale drawing questions in aptitude tests.