## iwanttogotostanford one year ago ACT PREP QUESTION NEED HELP: Which of the following sets of 3 numbers could be the side lengths, in meters, of a 30 degree -60 degree -90 degree triangle??? A. 1,1,1 B. 1, 1 , sqr root2 C. 1, sqr root 2, sqr root 2 D. 1, sqr root2, sqr root 3 E. 1, sqr root 3, 2

1. iwanttogotostanford

@zepdrix @Nnesha

2. zepdrix

Hmm I can't think of a way to explain this one without just giving the answer :P

3. misty1212

HI!!

4. misty1212

neither can i because what you need to know is ratio of a 30-60-90 right triangle are $1:\sqrt3:2$ for short leg : long leg : hypotenuse

5. iwanttogotostanford

well i already know the answer because i am using a ACT prep book i just need to know how to figure it out for future

6. misty1212

there is no other way to say it than just to say it that actually happens to be one of your answer, but so would $2,2\sqrt3,4$

7. iwanttogotostanford

all i need to know is how i can remember problems like it for the ACT

8. misty1212

or $\frac{1}{\sqrt3},1,\frac{2}{\sqrt3}$

9. iwanttogotostanford

i dont understand this problem at all..

10. misty1212

it is always true that the ration of a 30-60-90 right triangle are $\huge 1:\sqrt3:2$ what is what you need to know it is a fact

11. misty1212

*ratios

12. iwanttogotostanford

so its just basically a rule i need to know? no real figuring here?

13. misty1212

so for example if the short leg hat measure $$10$$ then the long leg would have measure $$10\sqrt3$$ and the hypotenuse would measure $$20$$

14. misty1212

you can derive it, but you don't want to have to do that on the fly remembering is best

15. iwanttogotostanford

so its a rule they want me to know? an thanks!

16. misty1212

yes, it is used in trig all the time

17. iwanttogotostanford

ah ok i haven't reached trig yet I'm in alg. 2 right now, thanks!

18. misty1212

$\color\magenta\heartsuit$