## lilg132 Group Title trigonometry help 2 years ago 2 years ago

1. lilg132

|dw:1328053926336:dw|

2. lilg132

i need to work out the length of BC and the phi angle

3. Mertsj

Law of Cosines: c^2=5^2+862-2(5)(8)cos 115.

4. Mertsj

$(BC)^2=5^2+8^2-2\times5\times8\cos 115$

5. lilg132

i've been taught just to do (bc)^2 = ac^2 + ab^2

6. Mertsj

then after you find BC use the law of sines.$\frac{\sin 115}{BC}=\frac{\sin \theta}{5}$

7. Mertsj

this is not a right triangle so the pythagorean theorem does not apply.

8. lilg132

ohhh ok

9. lilg132

i thought i was doing something wrong :p

10. lilg132

let me try and do it now thanks for pointing that out

11. Mertsj

yw