Question

In triangle ABC, measure of angle A=33, a=12,b=15, what is the measure of angle b to the nearest degree?

Answer 1

@geoffb

Answer 2

Are you given a diagram?

You should be able to use sin, cos, or tan to find angle B, since you know two sides (a and b).

Answer 3

Does it look like that?

Answer 4

If so, use a rule like \(\tan B = \frac{15}{12}\), though it might be different depending on your diagram.

Answer 5

my diagram looks exactly like yours

Answer 6

Perfect! You can solve for B using \(\tan^{-1} (\frac{15}{12})\) then.

Answer 7

i got a long decimal, although the choices im giveb are all whole numbers

Answer 8

Okay, wait...

If the triangle was a right-angle triangle, you could have solved for B by simply subtracting 90-33. So I imagine that's not the case.

It's not a right-angle triangle, I'm guessing.

Answer 9

wait, dont i use the law of sine?

Answer 10

Yes.

Answer 11

idk man do you know why i keep getting the decimal, all im doing is putting in the inverse of tan(15/12) into my calculator

Answer 12

No, forget I said that. That was for a right-angle triangle.

Like you said, you need to use the law of sines.

\(\Large\frac{a}{\sin A} = \frac{b}{\sin B}\)

\(\Large\frac{12}{\sin 33} = \frac{15}{\sin B}\)

Answer 13

\[\sin B = \frac{15 \sin 33}{12}\]

Answer 14

Is 43 one of the possible answers?

Answer 15

yea, so i dont find the inverse?

Answer 16

Yes, you do. We got:
\[\sin B = \frac{15 \sin 33}{12}\]
so...
\[B = \sin^{-1} (\frac{15 \sin 33}{12})\]

Answer 17

I see now, thanks out :D

Answer 18

No problem. Have a good night. :)

Answer 19

same for you :)