**The perimeter of a triangular field is 240dm. If two of its sides are 50 dm , and**

** 78 dm , find the length of the perpendicular on the side of length 50 dm from the **

** opposite vertex. Calculate also the cost of watering it as Rs.2.75 per 100 m ^{2} **

Now, let a = 50 dm , b = 78 dm and c = 112 dm.

So, Area of , where *s* is the semi - perimeter of the triangle.

∴ semi - perimeter of .

⇒

∴ Area of triangle,

= ..... (1)

Also. area of triangle = .... (2)

Equating (1) and (2), we get

⇒ h = 67.2 dm

Area of triangle = 1680 dm^{2}

We know that, 1 dm = 0.1 m

So, 1 dm^{2} = 0.1 × 0.1 m^{2} = 0.01 m^{2}

Hence, area of triangle = 1680 × 0.01 m^{2} = 16.8 m^{2}

Given, cost of watering for 100 m^{2} = Rs.2.75

So, cost of watering for 16.8 m^{2} =

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