Difficulty: Easy
Correct Answer: 6 cm
Explanation:
Introduction / Context: This problem tests the basic area formula of a parallelogram: area = base * height. When a relationship between base and height is given (here base is twice the height), you can substitute that relationship into the area formula and solve for the height directly.
Given Data / Assumptions:
Concept / Approach: Substitute b = 2h into A = b*h. This gives A = 2h^2, which can be solved by simple algebra to find h.
Step-by-Step Solution: A = b*h 72 = (2h)*h 72 = 2h^2 h^2 = 72/2 = 36 h = sqrt(36) = 6 cm
Verification / Alternative check: If height is 6 cm, then base = 2*6 = 12 cm. Area = 12*6 = 72 cm^2, matching the given area.
Why Other Options Are Wrong: 3 cm: would give base 6 cm, area 18 cm^2. 4 cm: would give base 8 cm, area 32 cm^2. 8 cm: would give base 16 cm, area 128 cm^2. 12 cm: would give base 24 cm, area 288 cm^2.
Common Pitfalls: Using triangle formula (1/2*b*h) by mistake. Forgetting that base is twice height and swapping them. Making an error when taking square root.
Final Answer: Height = 6 cm
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