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Olympiad workbook
Exam
Olympiad workbook
Subject
IOQM
Chapter
Straight Lines

Olympiad workbook · IOQM · Straight Lines

An ant leaves the anthill for its morning exercise. It walks 4 feet...

An ant leaves the anthill for its morning exercise. It walks 4 feet east and then makes a 160∘160^{\circ} turn to the right and walks 4 more feet. It then makes another 160∘160^{\circ} turn to the right and walks 4 more feet. If the ant continues this pattern until it reaches the anthill again, what is the distance in feet it would have walked?An ant leaves the anthill for its morning exercise. It walks 4 feet east and then makes a 160^ turn to the right and

Correct answer

36

Step-by-step solution

An ant leaves the anthill for its morning exercise. It walks 4 feet east and then makes a 160^ turn to the right and
 Let A0(0,0)A1(4cos⁡0,4sin⁡0)A2(4cos⁡0+4cos⁡160,4sin⁡0+4sin⁡160)An=(0,0)⇒4(cos⁡0+cos⁡160+…..+cos⁡160(n−1))=0 and 4(sin⁡0+sin⁡160+…..+sin⁡160(n−1))=0⇒sin⁡(80n)=0⇒n=9⇒ distance  covered =4×9=36 feet \begin{aligned} & \text { Let } A_0(0,0) \\ & A_1(4 \cos 0,4 \sin 0) \\ & A_2(4 \cos 0+4 \cos 160,4 \sin 0+4 \sin 160) \\ & A_n=(0,0) \\ & \Rightarrow 4(\cos 0+\cos 160+\ldots . .+\cos 160(n-1))=0 \text { and } 4(\sin 0+\sin 160+\ldots . .+\sin 160(n-1))=0 \\ & \Rightarrow \sin (80 n)=0 \\ & \Rightarrow \mathbf{n}=\mathbf{9} \\ & \Rightarrow \text { distance } \text { covered }=4 \times 9=36 \text { feet }\end{aligned}
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