Right triangle transformation and new hypotenuse:\nA right-angled triangle has hypotenuse 10 cm and area 24 cm^2. If the shorter leg is halved and the longer leg is doubled, find the length of the new hypotenuse.

Difficulty: Medium

Correct Answer: √265cm

Explanation:


Introduction / Context:
This problem uses two invariants of a right triangle—Pythagoras and area—to recover the legs, then applies specified changes to the legs and recomputes the hypotenuse.


Given Data / Assumptions:

  • Right triangle with legs a and b, hypotenuse 10 cm.
  • Area = 24 cm^2 → (1/2) * a * b = 24 → ab = 48.
  • Pythagoras: a^2 + b^2 = 10^2 = 100.
  • Shorter leg is halved; longer leg is doubled.


Concept / Approach:
From ab and a^2 + b^2, obtain (a + b)^2 = a^2 + b^2 + 2ab = 100 + 96 = 196 → a + b = 14. Solve a and b from t^2 − 14t + 48 = 0.


Step-by-Step Solution:

t^2 − 14t + 48 = 0 → (t − 6)(t − 8) = 0 → {a, b} = {6, 8}.Shorter = 6, longer = 8.New legs: 6/2 = 3 and 8*2 = 16.New hypotenuse = √(3^2 + 16^2) = √(9 + 256) = √265.


Verification / Alternative check:
Original: ab = 48 and a^2 + b^2 = 100 hold for 6 and 8. Transform as per instruction; recomputation matches √265 exactly.


Why Other Options Are Wrong:
√245, √255, √275, √225 are not equal to √(3^2 + 16^2).


Common Pitfalls:
Halving/doubling the wrong legs or attempting to scale the hypotenuse directly rather than recomputing with Pythagoras after the change.


Final Answer:
√265cm

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