a quarter is 1.75 mm thick
1 mm = 0.0393701 inches
0.0393701/12 = 25.4 mm per inch
25.4/1.75 = 14.5 quarters per inch
14.5 x 12 = 174 quarters per foot
174 x 0.25 = 43.50
$43.50 for a foot of quarters
You can use this to help you. label the triangle like the picture and use the equations. I hope this helps.
The expression that is not a variation of the Pythagorean identity is the third option.
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What is the Pythagorean identity?</h3>
The Pythagorean identity can be written as:

For example, if we subtract cos^2(x) on both sides we get the second option:

Which is a variation.
Now, let's divide both sides by cos^2(x).

Notice that the third expression in the options looks like this one, but the one on the right side is positive. The above expression is in did a variation of the Pythagorean identity, then the one written in the options (with the 1 instead of the -1) is incorrect, meaning that it is not a variation of the Pythagorean identity.
Concluding, the correct option is the third one.
If you want to learn more about the Pythagorean identity, you can read:
brainly.com/question/24287773
Divide the numbers for the unit rate and the rate is how much you side it by
For this case we have the following system of two equations with two unknowns:

Adding both equations we have to eliminate the variable "x":

Adding common terms, keeping in mind that different signs are subtracted and the sign of the major is placed:

Answer:

Option A