A bridge is made over the river which has constant width throughout- The bridge makes an angle of 30- from the direction of flow or makes an angle of 60- from a line perpendicular to the width of the river- If the length of the bridge is 100 m- then find the width of the river-A- 30 mB- 50 mC- 100 mD- 120 m

The correct option is B 50 m From the above diagram, cos 60^∘ = AB/100 1/2 = AB/100 AB = 50 m ...

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Standard IX

Mathematics

Calculating Heights and Distances

A bridge is m...

Question

A bridge is made over the river which has constant width throughout. The bridge makes an angle of $30^{\circ}$ from the direction of flow (or makes an angle of $60^{\circ}$ from a line perpendicular to the width of the river). If the length of the bridge is 100 m, then find the width of the river.

30 m

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50 m

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100 m

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120 m

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Solution

The correct option is B 50 m

From the above diagram,
$c o s 60^{\circ} = \frac{A B}{100}$
$\frac{1}{2} = \frac{A B}{100}$
$A B = 50 m$

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A bridge is made over the river which has constant width throughout. The bridge makes an angle of 30∘ from the direction of flow (or makes an angle of 60∘ from a line perpendicular to the width of the river). If the length of the bridge is 100 m, then find the width of the river.

The correct option is B 50 m From the above diagram, cos 60∘=AB100 12=AB100 AB=50 m

A bridge is made over the river which has constant width throughout. The bridge makes an angle of $30^{\circ}$ from the direction of flow (or makes an angle of $60^{\circ}$ from a line perpendicular to the width of the river). If the length of the bridge is 100 m, then find the width of the river.

The correct option is B 50 m

From the above diagram,
$c o s 60^{\circ} = \frac{A B}{100}$
$\frac{1}{2} = \frac{A B}{100}$
$A B = 50 m$