Answer: 1. 2262
Step-by-step explanation:
My guess is that you're doing the Law of Cosines? You have everything you need for that except the angle theta, which is the thing you need to find. It's set up like this: (8)^2 = (10)^2 + (5)^2 -[2(10)(5)cos A] I used A instead of theta. Doing that math, you have: 64 = 100 + 25 -[ 100 cos A]; 64 = 125 - 100 cos A;
-61 = - 100 cos A; -61 / -100 = cos A; .61 = cos A. Now use your inverse function on your calculator to find cos^-1(.61) and that equals 52.4
Your proportion should look something like this

After cross multiplication, you should end up with this equation

After dividing 4 on both sides, you should get that x=9
154.35 - 10.37 = 143.98
143.98 - 27.83 = 116.15
10.37 = 116.15x
x = 0.0893
Change x to percent form to get 8.93% tax rate.