## ashley_fay 2 years ago Find the value of x

1. ashley_fay

2. Azteck

triangle CDE is similar to BAC. Therefore you just use proportions.

3. Azteck

$\frac{ 42 }{ 6 }=\frac{ x }{ 32-x }$ Solve for x.

4. Azteck

I'm not sure if there's more to the question, but if there is and you're learning similarity, then it's certain that's what you should do. But if not, then it's a doozy. I will have to take another look at it later.

5. ashley_fay

it just says to round your answer to two decimal places. thanks for the help

6. Azteck

@ashley_fay Are you learning similarity at school?

7. ashley_fay

i was earlier but that was at the beginning of the unit and i kind of forgot about it.

8. Azteck

What topic is this on? When you got these questions, what topic is this?

9. ashley_fay

studying for the unit quiz

10. Azteck

That doesn't give me a clue what topic you're learning when you got these questions.

11. ashley_fay

ummm Geometry?? well the practice is a review over the whole unit soo thats why i said that but before this practice i was learning about trigonometric ratios

12. Azteck

Does the question just say find the value of x. Is there more to it? Does the image have any parallel lines or angles involved?

13. ashley_fay

it says: Given that triangle ABC~triangle DEC, Find the value of x. If necessary round your answer to two decimal points

14. ashley_fay

i put the same exact image on here

15. Azteck

See, you only gave "solve for x instead of the whole question word for word. That's just leaving out vital information.

16. Azteck

So I was correct. Read what I wrote above and solve for x.

17. ashley_fay

x=28

does the line of BC perpendicular with line CE ?? is there sign right angles there ??

if yes, use the similarity property and we get the proportion : x/6 = 42/(32-x) solve for x

@Azteck, which triangles were similar ? i think u take incorrect proportion ?

|dw:1359767903897:dw|

so, x/6 = 42/(32-x) , simplify x(32-x) = 6(42) 32x-x^2 = 6(42) x^2 - 32x + 6(42) = 0 (x-14)(x-18) = 0 solve for x by take the zeroes each terms .. (there are 2 x's are possible)

23. Azteck

ABC is similar to DEC...Angle B is equal to angle E.

24. Azteck

Angle A is equal to Angle D....

25. Azteck

Angle C is equal to Angle C....

26. Azteck

can u give some reason that angle C is equal to angle C, while the measure of angle C is not known :P

but if u look my diagram, in triangle ABC exactly : mACB + mABC = 90 or alpha + mABC = 90 degrees or mABC = 90-alpha ... (1) mACB + mBCE + mDCE = 180 or mACB + 90 + mDCE = 180 (supplement angles) mACB + mDCE = 180-90 mACB + mDCE = 90 alpha + mDCE = 90 mDCE = 90 - alpha ... (2) (1) = (2), that's why mABC = mDCE

29. Azteck

Look at your angles...Your angles are muddled up. How do you know that EDA is 90 degrees. That's your assumption. The question only gave a statement saying that there two triangles which are similar. It doesn't say "the angle is 90 degrees, etc. You will instantly be incorrect if you don't abide to the quesiton and create something out of thin air...

30. Azteck

there are two*

31. Azteck

"can u give some reason that angle C is equal to angle C, while the measure of angle C is not known :P " This is where the top students know what to do. They use there brain and the question to their advantage. the question says "Given that triangle ABC~triangle DEC, Find the value of x. If necessary round your answer to two decimal points " Now here's the trick, I will draw it for you.

32. Azteck

|dw:1359925509626:dw| Each angle corresponds wiht the other angle in relation to where they are put in order. If it was ACB is similar to DEC, then Angle C is equal to angle E.

33. Azteck

These are very minor things that place the average students and talented students in different positions. That's something you should know.