# Thread: Geometry:Similar Triangles

1. ## Geometry:Similar Triangles

Just want to know if i got this right guys. Im trying very hard now and i got serious with school im getting good grades ! thanks guys.
But here i got this similar triangles questions. They are done... is just to know if im right

2. These triangles are not similar. 4/12 is not equal to 20/15.

-Dan

PS Okay, I appear to be wrong. I'll check out why later.

Ah. I see now. That is a "y" not a 4. Please excuse.

3. Originally Posted by topsquark
These triangles are not similar. 4/12 is not equal to 20/15.

-Dan
Ratios

4. Yes, that's fine.

You can think of the sides of LMN are magnified by the exact same amount
to be the sides of PQR.

Let k be the magnification factor

$\displaystyle k[MN]=[QR]\Rightarrow\ k=\frac{[QR]}{[MN]}$

$\displaystyle k[LM]=[PQ]\Rightarrow\ k=\frac{[PQ]}{[LM]}$

$\displaystyle k[LN]=[PR]\Rightarrow\ k=\frac{[PR]}{[LN]}$

Therefore

$\displaystyle \frac{y}{12}=\frac{x}{18}=\frac{20}{15}$

or

$\displaystyle \frac{y}{20}=\frac{12}{15}$

$\displaystyle \frac{x}{20}=\frac{18}{15}$

5. Originally Posted by Archie Meade
Yes, that's fine.

You can think of the sides of LMN are magnified by the exact same amount
to be the sides of PQR.

Let k be the magnification factor

$\displaystyle k[MN]=[QR]\Rightarrow\ k=\frac{[QR]}{[MN]}$

$\displaystyle k[LM]=[PQ]\Rightarrow\ k=\frac{[PQ]}{[LM]}$

$\displaystyle k[LN]=[PQ]\Rightarrow\ k=\frac{[PQ]}{[LN]}$

Therefore

$\displaystyle \frac{y}{12}=\frac{x}{18}=\frac{20}{15}$

or

$\displaystyle \frac{y}{20}=\frac{12}{15}$

$\displaystyle \frac{x}{20}=\frac{18}{15}$
Thanks i knew i was getting good at this. Sorry for not pointing out it was a fraction

6. Note there was a typo in my post.

7. Originally Posted by Archie Meade
Note there was a typo in my post.
Sorry if i dont understand much but is TYPO an error?

8. yes, a writing error, I had written PQ a 2nd time instead of PR.

9. NP Just have to thank you !