In each triangle in the diagram, the measurements that are labeled are known, while the other measurements are unknown. In which triangle can you directly substitute known values into the Law of Cosines to find an unknown side or angle?

Question

anonymous · Answer

attachment

anonymous · Answer

@amistre64 i need help please

anonymous · Answer

@tkhunny pretty please help me

amistre64 · Answer

the law of cosine:

c^2 = a^2 + b^2 - 2ab cos(C)

as such, it is composed of 3 sides and an angle.

if we know any 3 of those things, we can solve for the 4th

tkhunny · Answer

@jassm1238872211 
Please state the Law of Cosines.
Don't post with NO work shown.  You MUST have something.
You could have stated the Law of Cosines.  That would have been something.

anonymous · Answer

there is a reason why i post it because i dont know how to do it???

anonymous · Answer

how can i show my work if i dont have a clue what to do

tkhunny · Answer

I did not say "know how to do it".  I said to give us ANYTHING.  Giving nothing is not acceptable to the Code of Conduct.  You MUST have a clue.  If you TRULY have NO clue. you are in the wrong class and need to go have a sincere chat with your academic adviser.

Are you saying you have no idea what the Law of Cosines is?  I simply don't believe that.

anonymous · Answer

i do know what the law of cosine is  but do not know what the right answer is

tkhunny · Answer

There, see, that's something.  Did you read amistre64's post?  That will lead you to the correct answer.

anonymous · Answer

but my answer choices is not making sense or is  just probably me

anonymous · Answer

so my answer is XYZ @amistre64

amistre64 · Answer

we must know 3 things: out of the four {a,b,c,C}

therefore, 

3 sides (a,b,c)

or 2 sides and an angle: (a,b,C), (a,c,C), (b,c,C)

amistre64 · Answer

XYZ we only know 3 angles, this is not a case of 3 sides, or 2 sides and an angle

tkhunny · Answer

As a good general rule, don't look at the choices until you are ready to respond.  Sometimes it helps to look at the choices, just to rule out some weirdos, but generally, it's more confusing than helpful.

amistre64 · Answer

choices always confuse me :)  even if its only one

anonymous · Answer

omg i feel soo stupid :(

anonymous · Answer

i hate geometry

amistre64 · Answer

split it into cases

which option do we know all 3 sides for?

amistre64 · Answer

you might want to review the definitions for side, and angle ...

anonymous · Answer

im sorry i read wrong ABC have all 3 sides

amistre64 · Answer

still not correct ... a side is a line of a triangle,  and angle is what is stuck inside of a corner.

anonymous · Answer

PQR ?