Can someone tell me if I did this right?

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.

Question

Can someone tell me if I did this right?

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.

anonymous · Answer

attachment

misty1212 · Answer

HI!!

misty1212 · Answer

$$\[a^2=b^2+c^2-2bc\cos(A)$$
$$a^2=12^2+15^2-2\times 12\times 15\cos(60)$$

misty1212 · Answer

yeah $a^2=189$

anonymous · Answer

hi @misty1212 !! :) can you please tell me if I did this problem correctly??

misty1212 · Answer

and so $a=13.75$

misty1212 · Answer

looks good to me
not sure about all those stupid blanks you have to fill in, like you are a child painting by numbers, but your answers are right

misty1212 · Answer

oh yes, they are right too
nice

anonymous · Answer

okay can I send you screenshots of my other work and can you tell me if I did them right? I keep getting a 60 on this lesson. @misty1212

misty1212 · Answer

sure

anonymous · Answer

this is number 1. @misty1212

misty1212 · Answer

this going to take a second

anonymous · Answer

2.

misty1212 · Answer

lets do the first one first

anonymous · Answer

okay :) @misty1212

misty1212 · Answer

i need to crank up the calculator

anonymous · Answer

lol alright.

misty1212 · Answer

check my work, but i get $3.5$ for the first one http://www.wolframalpha.com/input/?i=sqrt%287%5E2%2B4%5E2-2*7*4*cos%2820%29%29

anonymous · Answer

yeah that's what I got too. so the problem is false @misty1212

misty1212 · Answer

right false

misty1212 · Answer

second one is another law of cosines too right?

misty1212 · Answer

|dw:1432172045725:dw|

misty1212 · Answer

i get 105, not what you got

misty1212 · Answer

http://www.wolframalpha.com/input/?i=sqrt%2870%5E2%2B40%5E2-2*70*40*cos%28144%29%29

misty1212 · Answer

i think i did it right

anonymous · Answer

yeah I think so too thank you! do you know if I did this one right? @misty1212

misty1212 · Answer

looks like yet another law of cosines problem although we could use the law of sines too

misty1212 · Answer

i get 1.8 too

anonymous · Answer

I though they were the same thing? @misty1212

misty1212 · Answer

no law of sines is easier

misty1212 · Answer

$$\frac{a}{\sin(A)}=\frac{b}{\sin(B)}=\frac{c}{\sin(C)}$$ it is just solving ratios

misty1212 · Answer

no matter your answer of 1.8 looks right to me

anonymous · Answer

oh okay got it. can you please help me with this one too? @misty1212

misty1212 · Answer

gonna law of cosines me to death!

misty1212 · Answer

yeah i get 7.9 so go with 8

anonymous · Answer

okay :) how bout this one?

misty1212 · Answer

what, now i gotta read?

misty1212 · Answer

ok yet another law of cosines
i got my template set up

misty1212 · Answer

i get 75

misty1212 · Answer

http://www.wolframalpha.com/input/?i=sqrt%2885%5E2%2B105%5E2-2*85*105cos%2845%29%29

anonymous · Answer

sorry for asking for so much but honestly your help, helped me a ton thank you @misty1212

misty1212 · Answer

you are welcome 
are you done?

anonymous · Answer

yeah :) I got my grade up to a 90% @misty1212 thanks once again!

misty1212 · Answer

yay !!$$\huge \color\magenta\heartsuit$$