The Shadow of a tower Standing on a Level ground is Found to be 40 m Longer when Suns Altitude is 30 than When it was 60. Find the Height of the tower | Bzziii
The shadow of a tower standing on a level ground is found to be 40 m longer when Suns altitude is 30 than when it was 60. Find the height of the tower. (Take = `\sqrt{3}` = 1.732)
Given tower be AB
When Sun's altitude is `60^0`
`\angle` ACB = `60^0`
& Length of shadow = BC
When Sun's altitude is `30^0`
`\angle` ADB = `30^0`
& Length of shadow = DB
Shadow is 40 m when angle changes from 60° to 30° CD = 40 m
We need to find height of tower i.e. AB Since tower is vertical to ground ∴ ∠ ABC = 90°
From (1) and (2)
`\frac{"AB"}{\sqrt{3}}` = `\sqrt{3}`AB - 40
AB = `\sqrt{3}` (`\sqrt{3}`AB) - 40 `\sqrt{3}`
AB = 3AB - 40 `\sqrt{3}`
40 `\sqrt{3}` = 3AB - AB
40 `\sqrt{3}` = 2AB
AB = `\frac{ 40 \sqrt{3}}{2}`
AB = 20`\sqrt{3}`
Hence, Height of the tower = AB = 20`\sqrt{3}`metre
When Sun's altitude is `60^0`
`\angle` ACB = `60^0`
& Length of shadow = BC
When Sun's altitude is `30^0`
`\angle` ADB = `30^0`
& Length of shadow = DB
Shadow is 40 m when angle changes from 60° to 30° CD = 40 m
We need to find height of tower i.e. AB Since tower is vertical to ground ∴ ∠ ABC = 90°
From (1) and (2)
`\frac{"AB"}{\sqrt{3}}` = `\sqrt{3}`AB - 40
AB = `\sqrt{3}` (`\sqrt{3}`AB) - 40 `\sqrt{3}`
AB = 3AB - 40 `\sqrt{3}`
40 `\sqrt{3}` = 3AB - AB
40 `\sqrt{3}` = 2AB
AB = `\frac{ 40 \sqrt{3}}{2}`
AB = 20`\sqrt{3}`
Hence, Height of the tower = AB = 20`\sqrt{3}`metre
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