Explanation
Correct answer: B.
Choice B is correct. The Pythagorean theorem states that for a right triangle, , where represents the length of the hypotenuse and and represent the lengths of the legs. It's given that in triangle , angle is a right angle. Therefore, triangle is a right triangle, where the hypotenuse is side and the legs are sides and . It's given that the lengths of sides and are and , respectively. Substituting these values for and in the formula yields , which is equivalent to , or . Taking the square root of both sides of this equation yields . Since represents the length of the hypotenuse, side , must be positive. Therefore, the length of side is .
Desmos solution:
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Reviewed and rewritten by CookSAT
Why the other choices are wrong
Choice A
Choice A is incorrect. This is the result of solving the equation , not .
Choice C
Choice C is incorrect. This is the result of solving the equation , not .
Choice D
Choice D is incorrect and may result from conceptual or calculation errors.