Emily778 2 years ago AO=12 and BC=25. What is AB? I think it's 37, but I'm not sure.

1. Emily778

2. whpalmer4

Close...

3. whpalmer4

What is the length of the hypotenuse (OB)?

4. ParthKohli

|dw:1369717643930:dw|

5. ParthKohli

\(OC = OA = 12\) because they are the radii of the same circle.

6. ParthKohli

Also, as whpalmer asked, what is the hypotenuse, or \(OB\)? A good start might be noticing that \(OB = OC + CB\).

7. whpalmer4

or, just tell us how you came up with 37...then we can see if it is a simple arithmetic error, or how you approached the problem, or whatever...

8. KenLJW

OB^2=OA^2+AB^2 if angle A = 90 37^2=12^2+AB^2 other wise you have the sine angle formula

9. whpalmer4

I assumed (and ParthKohli too, I'm sure) that because only one intersection point is shown, AB is tangent to the circle, which means that OAB is a right angle.

10. KenLJW

imagine A approaching C

11. KenLJW

Not enough information given without assumption angle A = pi/2

12. KenLJW

When you assume you make a retriceof u and me

13. KenLJW

retriceof u and me

14. KenLJW

I guess it doesn't like that word

15. Emily778

That didn't help at all. You never even told me how to get that answer....

16. whpalmer4

17. Emily778

18. whpalmer4

19. KenLJW

Solve 37^2=12^2+AB^2

20. Emily778

The numbers..DUH

21. Emily778

And uh...I need to know AB to do that. DUH!!

22. Kapt_Crazy

emily the ans for ab is 35. its a right angle triangle

23. qweqwe123123123123111

Now wait...you're going "duh" at everyone else and yet you can't figure out what AB is from the equation 37^2=12^2+AB^2 ???

24. KenLJW

I used the Pythagorean theorem a^2+b^2=h^2 h = sqrt(a^2+b^2) or in out case b=sqrt(h^2-a^2)

25. Emily778

@Kapt_Crazy So I was right? The answer is 35? :)

26. KenLJW

Generally you shouldn't just give quantity but show all work so it's easy checked or to show how it's done

27. KenLJW

not give

28. Kapt_Crazy

yeah u right :)

29. qweqwe123123123123111

No, you didn't say 35. You said "I think it's 37" which you absurdly arrived at by adding AO and BC together. Also, 35 is only correct if AB is tangent to the circle at A. But since that information isn't given, then its only an assumption.

30. Kapt_Crazy

qweqwe if it was not a right angle triangle they would give u more info, like one of the angles or sumthing

31. Emily778

Oh, thankyou for going back and checking if I said 35. :) @qweqwe123123123123111

32. KenLJW

Yes they would have to give 2 angles to solve

33. qweqwe123123123123111

The assumption is probably a safe one, @Kapt_Crazy, But UNLESS THAT INFO IS GIVEN EXPLICITLY, it's still just an assumption. And the number of poorly formed and incomplete problems that are posted here every single day are legion, so there's no good reason to assume that this problem is stated any better than any other.