Answer:
A rectangle is a good, simple shape to begin with. The area of a rectangle is equal to the product of the length of its base and the length of its height. The height is a segment that is perpendicular to the base. For a rectangle, the base and height are often called the "length" and the "width", and sometimes the height is referred to as the "altitude."
Step-by-step explanation
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I pretty sure the form is 2, and she bought 10 books, 5b-7=58
2nd and 3rd ones a squared + b squared = c squared

We have to use the formula:

So,

Also, it will be

Hope you could understand.
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