Whether the answer is positive or negative depends on the number of positive and negative values in the question. The rules are exactly the same as to whether an answer is positive or negative. In the case of fractions, the rules for multiplying fractions apply as well (the numerators in the expression multiply to produce the product's numerator; the denominators in the expression multiply to produce the product's denominator) and the answer should be reduced to lowest terms.
If there is an odd number of negative terms, the answer will be negative.
If there is an even number of negative terms, the answer will be positive.
So basically you need to use the pythagorean thrm. Essentially, the diagonal and the width and length create a triangle, the diagonal being the hypothenuse. So the formula goes as . the variable "a" being the length and the variable "b" being the width. So plug it in and there you have your answer!
