500 or 600 depending on the maths question
The expression that is not a variation of the Pythagorean identity is the third option.
<h3>
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
Answer:
Randy had 13 books an Sandy had 7 books.
Step-by-step explanation:
20 - 3 = 17
30 - 17 = 13
13 x 2 = 26
26 + 4 = 30
13 + 7 = 20
Hope this helps! Please mark as brainliest.
Answer: What do you need, what grade are you in?
Step-by-step explanation:
Answer:

Step-by-step explanation:
The side that is parallel to BC is EF
Find the slope of EF:

Easiest way is just put the formula in point-slope form and simplify.
Let's use point F, which is (6,2)

Simplify:

Add 2 on both sides:

Hope this helped