## luisz 3 years ago what is the perimeter of triangle ABC?

1. pitankar

sum of the three side's length.

2. luisz

|dw:1347812022332:dw|

3. luisz

tips?

4. hartnn

there is a 30-60-90 triangle, u know the property of this special triangle ??

5. luisz

yes

6. luisz

but I know none of the sides

7. luisz

And I do not know the angles for the other triangle with sides

8. luisz

I could assume that triangle ABC is a 30-60-90, right?

9. luisz

C=30 degrees

10. luisz

A=60 degrees

11. luisz

B=90 degrees?

12. pitankar

calculate the length of perpendicular from A to BC using Pythagoras theorem. then use trigonometry relations to calculate AC. rest you can get...

13. hartnn

use pythagoras theorem to find the side...\|dw:1347812215548:dw|

14. luisz

ahh

15. luisz

good ol' pythagorean theorem

16. luisz

so we have a 9-12-15 right triangle

17. luisz

3-4-5?

18. luisz

so the altitude becomes 12

19. hartnn

now AD = 12 can u find all sides ?

20. luisz

30 degree side becomes 12 radical 3

21. luisz

AC equals 24

22. luisz

now

23. luisz

15+24=39

24. hartnn

use pythagoras

25. luisz

39+9=48

26. luisz

27. luisz

is that really it?

28. luisz

No wonder this problem was so hard

29. luisz

I never used pythagorean theorem

30. luisz

derp

31. hartnn

u did this by yourself :)

32. chihiroasleaf

you have lots of geometry problem @luisz :p

33. luisz

ty

34. luisz

I know