Given b = 12, c = 15 and A = 60° in triangle ABC, use the Law of Cosines to solve for a. Fill in the blank(s) to complete each step. If applicable, be sure to enter all decimal numbers with a zero in the ones place. Round your final answer to the nearest hundredth.
please show work and answer, very very confused. Thank you so much:)

Question

Given b = 12, c = 15 and A = 60° in triangle ABC, use the Law of Cosines to solve for a. Fill in the blank(s) to complete each step. If applicable, be sure to enter all decimal numbers with a zero in the ones place. Round your final answer to the nearest hundredth.
please show work and answer, very very confused. Thank you so much:)

sepeario · Answer

Do you know what the law of cosines is?

sepeario · Answer

attachment

sepeario · Answer

Substituting values from this triangle: |dw:1431766743710:dw|

sepeario · Answer

$$a ^{2}=12^{2}+15^{2}-2*15*12(\cos60)$$

sepeario · Answer

Would you like to solve from here?

anonymous · Answer

Im still very confused, i have big problem with numbers... the question is very overwhelming to me as well

anonymous · Answer

attachment

sepeario · Answer

okay. Look at the original equation. The first spot looks like the value of length b, the value of c has already been filled in.

sepeario · Answer

all you have to do is substitute values into that program, it essentially does the calculation for you.

mrnood · Answer

@helpmedearlord 
What do you actually want from this question

@Sepeario has given you the formula and given you the substitution or the numbers for your instance.

All that remains is to use a calculator to work out a from th eequation you are given.

There will be presumably many more questions like this in your study - do you want someone ot give oyu all the answers?

anonymous · Answer

This is the only question I asked for an answer flat out. That is because I am afraid of entering the wrong thing. I am very overwhelmed. I want the answer, but I want to know how to do this.

anonymous · Answer

It is also 2 am, so i am having a very hard time thinking as well. I really just want to finish my math class.

mrnood · Answer

you are told in the question to use the cosine formula

have oyu studied that formula?

@Sepeario gave the formula in his first post

you just need to look at the triangle you are given, and identify a,b,c,A,B &C

It doesn't matter which ones you call a , so long as you are consistent i.e a is opposite A

THEN use the formula and the calculator to solve the equation

anonymous · Answer

this is what I have rn

anonymous · Answer

omg nevermind i get it im just tired thank you all so much sorry for the trouble

sepeario · Answer

:)