Question

The following figure is drawn to find the distance across a lake, CD.

(See picture below)

Based on the given information in the figure, what is the distance across the lake?

*Select one answer*
80 m
60.25 m
20.25 m
There is not enough information to decide.

Please give the answer if you know that it is correct! Thank you for your help!!

Answer 1

Hello!

To do this, we know the two triangles are similar, so we can set up a proportion, and then find the length of the lake.

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The two triangles (Triangle AEB and ADC) are similar. We know this because all the angles have the same measurement - They all share angle A, they both have a right angle, and therefore, their third angle measures the same.

What we know about both triangles is their hypotenuse length. We know that triangle AEB has a hypotenuse that measures 320 m, and ADC has a hypotenuse that measures 320 + 162, or 482 m.

320 : 482 is therefore the ratio between the side lengths of two triangles (AEB : ADC). We can simplify this to 160 : 241.

Now, what we are looking for is the side length DC. The corresponding side to this in triangle AEB is EB, and we know it measures 40 m. Therefore, using the ratio, we can find the measure of DC.

160 / 4 : 241 / 4

40 : 60.25

Therefore, the measure of DC is 60.25 m.

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Hope this helps!