She would save 54.45 because addding them up individually before the plan would cost 184.49 and to find the difference all you have to do is subtract 184.49-129.99 and that would tell you how much she saved
Tan(a/2) = sin a / (1 + cos a)
tan(45/2) = sin(45) / (1 + cos(45)) = (1/√2) / (1 + 1/√2) = (1/√2) / (√2 + 1)/√2 = 1/(√2 + 1) = (√2 - 1)
Ah...Trigonometry is fun!
The law of sines states:

The transitive property (switching the orders of the equations) applies here. Therfore, we can say that

We then plug in our given values to find C


Solving, we get 0.8557316387.
We're not done yet!We are trying to find an angle measure, so we'll do the inverse of the ratio we used (sin).
arcsin0.8557316387 (arcsin is the same as inverse sin)
=
58.8 (approximate)
So the measure of angle C is 58.8. You could check this by reinserting it into the equation

.
:)