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Example 2 - An electrician has to repair an electric fault - Questions easy to difficult


Example 2 An electrician has to repair an electric fault on a pole of height 5 m. She needs to reach a point 1.3m below the top of the pole to undertake the repair work. What should be the length of the ladder that she should use which, when inclined at an angle of 60° to the horizontal, would enable her to reach the required position? Also, how far from the foot of the pole should she place the foot of the ladder? (You may take √3 = 1.73) Given, the height of the pole = 5 meter. So, AD = 5 m BD = AD – AB BD = 5 – 1.3 = 3.7 m Here, we have to find the length of ladder, i.e. BC & distance from foot of the ladder to the foot of the pole, i.e. DC Finding length of ladder Since pole is vertical to ground ∠BDC = 90° Finding distance from foot of pole to foot of ladder In right angle triangle BCD, tan C = (𝑆𝑖𝑑𝑒 𝑜𝑝𝑝𝑜𝑠𝑖𝑡𝑒 𝑡𝑜 𝑎𝑛𝑔𝑙𝑒" " 𝐶)/(𝑆𝑖𝑑𝑒 𝑎𝑑𝑗𝑎𝑐𝑒𝑛𝑡 𝑡𝑜 𝑎𝑛𝑔𝑙𝑒" " 𝐶) tan 60° = 𝐵𝐷/𝐶𝐷 √3 = 𝐵𝐷/𝐶𝐷 √3 = 3.7/𝐶𝐷 CD = 3.7/√3 CD = 3.7/1.73 CD = 2.14m Hence, Distance from foot of pole to foot of ladder = CD = 2.14m

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He provides courses for Mathematics from Class 9 to 12. You can contact him here.
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  • kana jhanwar's image
    The line joining the top of a hill to the foot of the heal makes angle of 30°with the horizontal through the the foot of the hill . There is one Temple at the top of the hill and a guest house half way from the foot to the top. The top of the temple end of the guest house both make and elevation of 45° at the foot of the hill. If the guest house is 1 km away from the foot of the hill along the hill. Find the heights of the guest house and the temple?

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