Question

Help with this please? =)
Find AC. Round to the nearest tenth.

Answer 1

First of all I would label the the lengths accordingly,
a common way to do this is to label it with a lower case letter of the angle it is opposite

So AC=b
BC=a
AB=c

So you want to find length 'b'

Using the cosine rule, we know that:

\[b ^{2} = a ^{2} + c ^{2} -2ac \cos B\]

you already have the values necessary to find your length AC, so just plug in the values

\[b ^{2} = 12^{2} + 10^{2} - 2*10*12 (\cos 105)\]
then take the square root to find 'b'

Hope this cleared it up :)

Answer 2

Wow you're amazing! Thanks so much!

Answer 3

remember if i have 2 known sides which emanate to give a known, u simply use the cosine rule if it is not a right triangle

Answer 4

Got it. Thanks!

Answer 5

known angle*

Answer 6

@catsarecool1995 no problem!