SOLUTION: Recall that the lengths of the sides of triangle ABC are often abbreviated by writing a = BC, b = CA, and c = AB. Sketch triangle ABC where angle BCA is right and mark F as the foo

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Question 1159001: Recall that the lengths of the sides of triangle ABC are often abbreviated by writing a = BC, b = CA, and c = AB. Sketch triangle ABC where angle BCA is right and mark F as the foot of the perpendicular drawn from C to the hypotenuse AB. In terms of a, b, and c, express the lengths of FA, FB, and FC. The equation c = FA+FB can be used to check your work.
Answer by KMST(5396) About Me  (Show Source):
You can put this solution on YOUR website!
This is our first triangle: triangle ABC
When I draw the perpendicular from C to hypotenuse AB, we will have point F, and the first triangle will be split into 2 triangles.
I will labeled them as triangle #2 and triangle #3.

Triangle ABC, triangle #2, and triangle #3 are similar triangles. They have the same shape, the same angle measures, and the same ratios of corresponding sides.
For the ratio of side opposite alpha to hypotenuse we have:
b%2Fc=FC%2Fa=FA%2Fb --> system%28highlight%28FC=ab%2Fc%29%2Chighlight%28FA=b%5E2%2Fc%29%29
For the ratio of side opposite beta to hypotenuse we have:
a%2Fc=FB%2Fa=FC%2Fb --> system%28highlight%28FB=a%5E2%2Fc%29%2CFC=ab%2Fc%29
Of course, we know that FA%2BFB=BC=c ,
We can verify that the expressions we found for FA and FB are correct, by substituting, and finding that it agrees with what we know:
From c=FA%2BFB --> c=b%5E2%2Fc%2Ba%5E2%2Fc --> c=%28b%5E2%2Ba%5E2%29%2Fc --> c%5E2=b%5E2%2Ba%5E2 .
However, along the way, we find that we proved the Pythagorean theorem from our knowledge about similar triangles.
We can also prove that FC%5E2=FA%2AFC <--> FC=sqrt%28FA%2AFC%29 .