## a1234 one year ago a = 5 and c = 20. Find A and round to two decimal places.

1. a1234

|dw:1444623329598:dw| Is A equal to 14.48 degrees?

2. anonymous

Are you familiar with the law of sines?

3. a1234

Yes, but I don't think they're needed here. sinA = 5/20 A = sin^-1 * 5/20

4. anonymous

It makes things a bit easier LAW OF SINES: $\frac{ \sin(A) }{ a }=\frac{ \sin(B) }{ b }$ Plug in what we know $\frac{ \sin(90) }{ 20 }=\frac{ \sin(A) }{ 5 }$ $A=\sin^{-1} (\frac{ 5\sin(90) }{ 20 })$

5. anonymous

Technically, the law applies to the whole triangle so it should be $\frac{ \sin(A) }{ a }=\frac{ \sin(B) }{ b }=\frac{ \sin(C) }{ c }$ But you get the idea

6. anonymous

7. anonymous

Eh, it doesn't make it simpler. But later on you'll see that it's great to have.

8. a1234

Yes, it can be useful, but maybe not in this particular case

9. a1234

Thanks!