I'm probably just stupid, but please help ;-;

C

Cafevoir

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"The relation of the sides of a rectangle is 3:4, and it's diagonal is 20cm. Calculate the area of the rectangle." (I don't know if the words are correct, I tried to translate it from Finnish, and sorry for my bad england). I think the picture shows what it looks like. Maybe. Not sure. HELP ME :(
 

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Since the sides are in a ratio of 3:4, the two sides with the diagonal form a 3-4-5 right triangle. The ratio of the diagonal to the sides is 3:5 and 4:5. You might say we have a right triangle of 3-4-5 dilated by a factor of 4. So the height is 12 (4 x 3) and the base is 16 (4 x 4). The area is then 12 x 16 = 192.

I hope this is clear.
 
I would call one side 3a and the other side 4a. So the area is 12a2. So we need to find a. Pythagorous would know how to do this!

(3a)2 + (4a)2 = 202. Solve this equation for a.
 
Jomo said:
I would call one side 3a and the other side 4a. So the area is 12a2. So we need to find a. Pythagorous would know how to do this!

(3a)2 + (4a)2 = 202. Solve this equation for a.
Click to expand...

Your answer was better than mine. I admire your style. Hopefully you will help me improve.
 
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