# Similar trianglesWatch

This discussion is closed.
#1
Please can somebody tell me how to do them, they are discombobulating me or does anyone know what they are called in the CGP books?

Thanks
Twaffy
0
13 years ago
#2
You just have to multiply the sides by some number to get the length of the second triangle.

For example, triangle 1 has this length: 6cm, while triangle 2 have this length: 12cm. Therefore you just have to multiply it by 2.

I think that's what you do.
0
#3
Yes but what do you do with the xs and ys?
Thanx anyways
0
13 years ago
#4
(Original post by Twaffy)
Yes but what do you do with the xs and ys?
Thanx anyways
I think you should type out the question or scan the question and post it up here, so we know what you mean.
0
13 years ago
#5
Are you thinking of some form of enlargement? (transformation) if you are applying similar triangles graphically.

If you are, and you have x and y coordinates for each, you can work out the side lengths by pythagoras, ie a edge with coordinates (2,4) and (6,3) at each end, you take the change in x (in this case 4) and change in y (3) and then apply pythagoras to get the length of the side (in this case its 5)

once you have the lengths of the side, you can use the above to get a similar triangle. although if its an enlargement you'd need a center.
0
13 years ago
#6
If as i understand it you are talking about mathematicailly similar triangles then the idea behind the question is to find out in what proportion the two triangles are to each other. An example: if one straight line is 5 cm long and another is 10 cm long then we can say that the second line is twice as long as the first.
Therefor if you are working out how much larger or smaller (the proportion) one triangle has to another you simply need to devide two corresponding sides by each other, find out the answer and then devide or multiply all other sides by that to work out the missing sides on the second triangle.
Ill try and give an example:
Triangle A- side x is 12 cm long. (other two sides are 5 (sidey)and 7(sidez) cm long)
Triangle B- corresponding side is 4 cm long.
Question: find the length of the corresponding sides to y and z
If we devide 12 by 4 we get 3 so we knoe that triangle A is 3 times larger than triangle B now we do the same for the other two sides: 5 devided by 3 and 7 devide by 3
i can t be bothered to get a calc but do you get my drift???
If not dont worry- its maths and therel only b a question or 2 on the paper aboput it
0
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