This is a data sufficiency question about a right-angled triangle. Question: What is the height (perpendicular) of the right-angled triangle? Statement A: The area of the triangle is 20 times its base. Statement B: The perimeter of the triangle is equal to the perimeter of a square having side 10 cm. Decide which statement(s) is/are sufficient to determine the height uniquely (without needing any additional information).

Difficulty: Hard

Correct Answer: Only statement A is sufficient

Explanation:


Introduction / Context:
Data sufficiency questions test whether given statements provide enough information to answer a question, not whether you can compute many values. Here, you must decide if the height of a right-angled triangle can be uniquely determined. The right-triangle area formula involves base and height directly, while the perimeter statement relates to side lengths but may not uniquely fix the height without additional relationships.


Given Data / Assumptions:

  • We need the triangle’s height (perpendicular to the base)
  • Right-angled triangle area formula: area = (1/2) * base * height
  • Statement A: area is 20 times the base
  • Statement B: triangle perimeter equals perimeter of a square of side 10 cm (so perimeter = 40 cm)


Concept / Approach:
Check each statement independently. A is sufficient if it directly yields height. B is sufficient only if perimeter alone uniquely determines height, which generally it does not for right triangles unless more constraints are provided.


Step-by-Step Solution:

Step 1: From statement A, area = 20 * base Step 2: Also, area = (1/2) * base * height Step 3: Set equal: (1/2) * base * height = 20 * base Step 4: Cancel base (base is non-zero for a triangle): (1/2) * height = 20 Step 5: height = 40 cm Step 6: From statement B, perimeter = 4 * 10 = 40 cm, but many different right triangles can have perimeter 40 cm, so height is not unique


Verification / Alternative check:
Statement A gives a single value height = 40 cm regardless of base, so it uniquely determines the height and is sufficient alone. Statement B gives only a perimeter total, which can correspond to multiple sets of sides (and thus multiple heights), so it is insufficient alone.


Why Other Options Are Wrong:

Only B: perimeter alone does not lock the height uniquely. Both A and B: A already determines height; B is unnecessary. Neither: A clearly gives height by direct area relationship. Either alone: only A works; B does not.


Common Pitfalls:
Many learners confuse data sufficiency with “can I compute something.” You must check uniqueness. Another mistake is forgetting that base cancels in statement A, making height independent of base value. For statement B, assuming a unique triangle from perimeter alone is incorrect.


Final Answer:
Only statement A is sufficient

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