As per convention:
- the angle at A is named A, the angle at B is named B, and the angle at C is named C
- the side of leght a is the side opposed to A, the side of length b is opposed to B, and the side of length c is opposed to C.
Now just state the law of cosines:
c^2 = a^2 + b^2 - 2ab cos(C)
Also, a^2 = c^2 + b^2 - 2bc cos (A)
And, b^2 = a^2 + c^2 - 2ac cos (B)
I think it's Persuasive..because it appeals to our emotions by getting us to agree with them, and it uses reason and logic to do so, and often uses statistics....and there's almost always a clear statement of what they want us to believe at the beginning
