Answer: Fourth option: y^2=9^2+19^2-2(9)(19) cos(41°)
The law of cosines to solve for one side is:
c^2=a^2+b^2-2ab cos C
We must know the other two sides (a and b) and the angle between these sides (angle C, the opposite to the side that we want to determine)
In this case c=y, a=9, b=19, and C=41°, then:
y^2=9^2+19^2-2(9)(19) cos (41°)
The result of the fraction is 3.5
we can calculate this like this:

I think that the question is asking between which two natural numbers the result lies, and the result is 3 and 4: it's bigger than 3 and smaller than 4
These triangles are congruent because of SAS so therefore 3x-5 =2x+1 and x=6
435 being the constant means that is what they started with
Hope this helps :)
Remember that

is

. We know form our problem that

and

, so:



Now, to find

, we just need to evaluate

at 3. In other words, we are going to replace

with 3:


We can conclude that the correct answer is <span>
C.6(3) – 4 + 3^2 </span>